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Full Descrption On all Types Of Networks

Mon, 25 Jan 2010 07:05:36 +0100

A computer network allows sharing of resources and information among devices connected to the network. The Advanced Research Projects Agency (ARPA) funded the design of the "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of Defense. It was the first operational computer network in the world.Development of the network began in 1969, based on designs developed during the 1960s. For a history see ARPANET, the first network.

Network classification

The following list presents categories used for classifying networks.

Connection method

Computer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as Optical fiber, Ethernet, Wireless LAN, HomePNA, Power line communication or G.hn. Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges and/or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium.

ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.

Wired Technologies

Twisted-Pair Wire - This is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second.

Coaxial Cable – These cables are widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.

Fiber Optics – These cables consist of one or more thin filaments of glass fiber wrapped in a protective layer. It transmits light which can travel over long distance and higher bandwidths. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed could go up to as high as trillions of bits per second. The speed of fiber optics is hundreds of times faster than coaxial cables and thousands of times faster than twisted-pair wire.

Wireless Technologies

Terrestrial Microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx. 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.

Communications Satellites – The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.

Cellular and PCS Systems – Use several radio communications technologies. The systems are divided to different geographic area. Each area has low-power transmitter or radio relay antenna device to relay calls from one area to the next area.

Wireless LANs – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANS use spread spectrum technology to enable communication between multiple devices in a limited area. Example of open-standard wireless radio-wave technology is IEEE 802.11b.

Bluetooth – A short range wireless technology. Operate at approx. 1Mbps with range from 10 to 100 meters. Bluetooth is an open wireless protocol for data exchange over short distances.

The Wireless Web – The wireless web refers to the use of the World Wide Web through equipments like cellular phones, pagers,PDAs, and other portable communications devices. The wireless web service offers anytime/anywhere connection.

Scale

Networks are often classified as Local Area Network (LAN), Wide Area Network (WAN), Metropolitan Area Network (MAN), Personal Area Network (PAN), Virtual Private Network (VPN), Campus Area Network (CAN), Storage Area Network (SAN), etc. depending on their scale, scope and purpose. Usage, trust levels and access rights often differ between these types of network - for example, LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations (such as a building), while WANs may connect physically separate parts of an organization to each other and may include connections to third parties.

Functional relationship (network architecture)

Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g., Active Networking, Client-server and Peer-to-peer (workgroup) architecture.

Network topology

Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network. Network topology signifies the way in which devices in the network see their logical relations to one another. The use of the term "logical" here is significant. That is, network topology is independent of the "physical" layout of the network. Even if networked computers are physically placed in a linear arrangement, if they are connected via a hub, the network has a Star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct; the logical network topology is not necessarily the same as the physical layout. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks.

Types of networks

Below is a list of the most common types of computer networks in order of scale.

Personal area network

A personal area network (PAN) is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. Such a PAN may include wired and wireless connections between devices. The reach of a PAN is typically at least about 20-30 feet (approximately 6-9 meters), but this is expected to increase with technology improvements.

Local area network

A local Area Network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines)

For example, a library may have a wired or wireless LAN for users to interconnect local devices (e.g., printers and servers) and to connect to the internet. On a wired LAN, PCs in the library are typically connected by category 5 (Cat5) cable, running the IEEE 802.3 protocol through a system of interconnected devices and eventually connect to the Internet. The cables to the servers are typically on Cat 5e enhanced cable, which will support IEEE 802.3 at 1 Gbit/s. A wireless LAN may exist using a different IEEE protocol, 802.11b, 802.11g or possibly 802.11n. The staff computers (bright green in the figure) can get to the color printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalog. Each workgroup can get to its local printer. Note that the printers are not accessible from outside their workgroup.

Typical library network, in a branching tree topology and controlled access to resources

All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers.

The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.

Campus area network

A campus area network (CAN) is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting.

In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).

The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base. A CAN may be considered a type of MAN (metropolitan area network), but is generally limited to a smaller area than a typical MAN. This term is most often used to discuss the implementation of networks for a contiguous area. This should not be confused with a Controller Area Network. A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings.

Metropolitan area network

A metropolitan area network (MAN) is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan area network.

Wide area network

A wide area network (WAN) is a computer network that covers a broad area (i.e. any network whose communications links cross metropolitan, regional, or national boundaries [1]). Less formally, a WAN is a network that uses routers and public communications links. Contrast with personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs), which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively. The largest and most well-known example of a WAN is the Internet. A WAN is a data communications network that covers a relatively broad geographic area (i.e. one city to another and one country to another country) and that often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.

Global area network

A global area networks (GAN) (see also IEEE 802.20) specification is in development by several groups, and there is no common definition. In general, however, a GAN is a model for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is "handing off" the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial WIRELESS local area networks (WLAN).

Virtual private network

A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.

A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.

A VPN allows computer users to appear to be editing from an IP address location other than the one which connects the actual computer to the Internet.

Internetwork

An Internetwork is the connection of two or more distinct computer networks or network segments via a common routing technology. The result is called an internetwork (often shortened to internet). Two or more networks or network segments connect using devices that operate at layer 3 (the 'network' layer) of the OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.

In modern practice, interconnected networks use the Internet Protocol. There are at least three variants of internetworks, depending on who administers and who participates in them:

Intranet
Extranet
Internet

Intranets and extranets may or may not have connections to the Internet. If connected to the Internet, the intranet or extranet is normally protected from being accessed from the Internet without proper authorization. The Internet is not considered to be a part of the intranet or extranet, although it may serve as a portal for access to portions of an extranet.

Intranet

An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.

Extranet

An extranet is a network or internetwork that is limited in scope to a single organization or entity and also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be given access to some part of its intranet creating in this way an extranet, while at the same time the customers may not be considered 'trusted' from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.

Internet

The Internet consists of a worldwide interconnection of governmental, academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW). The 'Internet' is most commonly spelled with a capital 'I' as a proper noun, for historical reasons and to distinguish it from other generic internetworks.

Participants in the Internet use a diverse array of methods of several hundred documented, and often standardized, protocols compatible with the Internet Protocol Suite and an addressing system (IP Addresses) administered by the Internet Assigned Numbers Authority and address registries. Service providers and large enterprises exchange information about the reachability of their address spaces through the Border Gateway Protocol (BGP), forming a redundant worldwide mesh of transmission paths.

Basic hardware components

All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber"). An Ethernet card may also be required.

Network interface cards

A network card, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.

Repeaters

A repeater is an electronic device that receives a signal, clean it from the unnecessary noise, regenerate it and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters.

Hubs

A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.

Bridges

A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.

Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.

Bridges come in three basic types:

Local bridges: Directly connect local area networks (LANs)
Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced with routers.
Wireless bridges: Can be used to join LANs or connect remote stations to LANs

Switches

A network switch is a device that forwards and filters OSI layer 2 datagrams (chunk of data communication) between ports (connected cables) based on the MAC addresses in the packets. This is distinct from a hub in that it only forwards the frames to the ports involved in the communication rather than all ports connected. A switch breaks the collision domain but represents itself a broadcast domain. Switches make forwarding decisions of frames on the basis of MAC addresses. A switch normally has numerous ports, facilitating a star topology for devices, and cascading additional switches.Some switches are capable of routing based on Layer 3 addressing or additional logical levels; these are called multi-layer switches. The term switch is used loosely in marketing to encompass devices including routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier).

Routers

A router is a networking device that forwards packets between networks using information in protocol headers and forwarding tables to determine the best next router for each packet. Routers work at the Network Layer (layer 3) of the OSI model and the Internet Layer of TCP/IP

Good Health Tips on Eyes,Skin,Hair

Mon, 25 Jan 2010 06:59:15 +0100

Health

The responsibility for health care is devolved to the constituent countries of the United Kingdom: England, Wales, Scotland and Northern Ireland. In all countries, health care is predominantly funded through national taxation. Within each county, the responsibility for purchasing health services is being devolved to local bodies (Primary Care Trusts in England, Health Boards in Scotland, local health groups in Wales and Primary Care Partnerships in Northern Ireland). Primary care services are mainly provided by GPs and multi-professional teams in health centres (under a capitated budget). Hospitals are mainly publicly owned with independent trust status. Private hospitals mainly provide services to privately insured patients or those who are willing to pay directly.

All legal residents of the United Kingdom and British Nationals are entitled to cover under the UK National Health Service (NHS). In addition residents of the European Economic Area (EEA) are entitled to care, as are residents and citizens of other countries with which the UK has reciprocal agreements Overseas Visitors. In the UK, 11.5% of the population have supplementary private medical insurance. Those most likely to have private medical insurance are in the higher income groups (40% of adults with private medical insurance are in the highest income decile compared to less than 5% in the lowest). According to data from the General Household Survey 1995 12% of those between 45-64 years old had private medical insurance compared to only 5% of those over 65 years old. Private medical insurance policy holders are concentrated in London and the South East of England. In Scotland and the North the figure is as low as 5% of the population.

More recently with the establishment of the National Institute for Clinical Excellence (NICE) recommendations are being made to the Secretary of State as to whether the NHS should cover certain services for all of the population or for certain indications or defined subgroups of the population. NICE is a special health authority and is accountable to the Secretary of State for Health in England and to the National Assembly for Wales. Its decisions are based on analysis of the costs and benefits of a particular technology by the Appraisal Committee NICE. NICE’s guidance is not yet mandatory though recent government announcements suggest this is likely to change.

Having lustrous and healthy hair is the dream of every woman. In today's world, hair increasingly plays a central role in how we present ourselves to the outside world. A healthy head of full and shining hair with no flakes or other visible damage is easy to spot.
Whatever healthy hair means to you, one universal fact is that a girl’s hair is her crowning glory. But what about when your crowning glory isn't quite so glorious? Your hair is one of the biggest first impressions people will get when they see you, as it complements all of your other features. Hence, it is essential to make sure that your hair is always at its best.

We provide you with hair care tips for maintaining and managing your hair. Through our range of articles on hair health, we give you tips on maintaining and managing your hair, how to choose the right shampoo and other hair care products and common hair problems.

True beauty is a reflection of true health, and true health begins deep inside each and every cell in your body. Looking good can make you feel good and your looks can often depict your personality and attitude. Nourishing and nurturing yourself properly can bring immense and immeasurable rewards of confidence, vitality, energy, optimism and good health. Your skin is an indicator of your general health. Acne, wrinkles, dry or oily skin and inflammation are all signs of poor internal health, often brought on by consuming unhealthy foods and avoiding skin-healthy nutrients.

Know your skin
Skin acts as a barrier between the outside world and the controlled environment within your body. It protects your body from dirt, bacteria, foreign objects, Ultraviolet Rays and plays a vital role in regulating body temperature and body fluids and helps in the synthesis of vitamin D. It has millions of nerve endings that help in sensing hot, cold, hard, sharp or dull sensations

Skin structure

Basically your skin is made up of three layers namely

Epidermis: This is the protective upper layer of your skin, which is tough. It provides your skin with resistance to physical wear and tear and also makes skin water proof.
Dermis: This layer of skin lies just below the epidermis and contain numerous supporting tissues, blood vessels, nerves, hair roots and sweat glands. The dermis has two types of proteins called the Collagen and elastin, which give your skin its strength and flexibility

Subcutaneous tissue: This is theinnermost layer of the skin, also made up of connective tissue, sweatglands, blood vessels and Cells that store fat. This layer

Know your skin type
It is important to know your skin type, as it can help you maintain your skin health by taking the right measures to promote optimum skin care.

There are five major types of skin:

Normal skin: This type of skin looks healthy as there is a right balance between oil and moisture content. The normal skin appears smooth, clear and toned, without spots or blemishes and reflects good health.

Oily skin: This type of skin appears greasy. Dirt and dust gets attracted by the excessive oil on the skin leading to black heads, white heads, pimples and spots.

Dry skin: This type of skin appears parched and flaky due to a lack of moisture caused by inadequate secretions of the Sebaceous Glands.

Combination skin: This type of skin appears dry at the cheeks and areas around the mouth and eyes and appears oily at the central panel (forehead, nose and chin). Hence, it is known as combination skin.

Sensitive skin: This type of skin has a fine texture and is sensitive to climatic changes and chemical ingredients present in perfumes, dyes and other cosmetic products

How to determine your skin type?
As you wake up in the morning check for the grease/oil on your face. Wipe your face with a tissue. If you observe oil on the tissue then your skin is the greasy type.

If you observe grease or oil only on the center panel or the T-zone (forehead, nose and chin), then it would be combination skin. If you do not observe any grease/oil on the tissue, then it is either normal or dry skin. Dry skin feels too tight, parched and stretched whereas a normal skin feels smooth, elastic and supple.

Common skin problems
There are numerous skin disorders and these may be categorized into nine common types.

Rashes: A rash appears red with inflammation. Rashes can occur due to allergy, infections, irritation, disease and other conditions like blocked pores or improper functioning of the oil glands in your skin. The examples are dermatitis, acne, eczema, psoriasis, etc.
Bacterial infections: These infections are caused when bacteria infect the upper layer of your skin, follicles and the inner most layer of your skin. The examples of bacterial skin infection include folliculitis, cellulites, etc.
Fungal infections: There are various fungi that are present on the surface of your
skin that are generally harmless. But skin infections can occur when these fungi gain entry into your body. These infections can affect your skin, hair and nails and sometimes
may lead to serious health conditions.
The examples include ringworm, athlete’s foot, etc.
Viral infections: This is caused when a virus infects the inner layer of your skin. Examples include measles, chicken pox, herpes, warts, etc.
Trauma: A trauma may be due to a cut, burn or a blow and the body becomes more prone to infections during these conditions.
Parasitic infections: These infections are caused by parasites like scabies and lice

Other conditions: There are various other skin conditions like wrinkles, Spider Veins and Rosacea caused due to enlargement of veins and/or breakdown of Collagen and Elastin.

Preventing skin problems
The natural process of aging and skin problems can be avoided by washing your skin gently, moisturizing skin regularly and avoiding overexposure to the sun. A few simple skin care habits (see box) can help keep your skin healthy and glowing for years to come.

Treatment for skin problems
There aremany different drugs, creams, and therapies for skin problems.Medications used to treat skin conditions usually include topical andoral medications. It is recommended that you seek your doctor’s adviceregarding treatment options. Your doctor knows what is best for you.

Good habits for healthy skin

Wear long-sleeved shirts, long pants and wide-brimmed hats.

Apply sunscreen 20 min before going outdoors.

Try avoiding outdoors during 10:00 am to 4:00 pm, since the sun rays are most damaging during these hours.

Adequate hydration is also important; drink at least 8–10 glasses of water.

Eat a healthy and balanced diet. Avoid fried and greasy foods.

Smoking can accelerate the normal aging process of the skin and also contribute to wrinkles.

Having long, hot showers can remove essential oils from skin.

Generally avoid soaps labeled "antibacterial" or "antimicrobial." These tend to reduce the skin's acidity, which acts as a protection from infection. Choose mild soaps with oils and fats.

People with sensitive skin should avoid dyes and perfume containing products.

After a bath, pat your skin dry gently with a towel so that some moisture remains.

Select a moisturizer with a sun protection factor (SPF) of at least 15 to help protect your skin from damaging Ultraviolet Rays.

Getting sufficient exercise gets the blood flow going and sends oxygen to the skin Cells.

Always consult your doctor to treat skin problems. Always clean your make-up before you sleep

Eye cosmetics

A simplest touch of a right eye makeup can make you smashingly beautiful and transformyou instantly. Eyes are considered to be the windows of the soul. They are the firstfeature to be noticed on your face. Eye cosmetics are widely used to enhance thebeauty of the eyes.

Eye shadows, eye liner and mascara are the most popular eye cosmetics and considered the basics for any makeup application. However, eye cosmetics can develop harmful effects on the eyes as well

Many instances of allergic reaction, infection or injury to the eye are a result of improper use of cosmetics rather then due to any of its ingredients. So it is important to follow some basic hygiene and cleanliness when using eye cosmetics

Eyeliners
Eyeliners are the most extensively used form of eye makeup. They are used to outlinethe eyes so that your eyes look more prominent and create an illusion of thickereyelashes. Eyeliners come in liquid or pencil forms. Liquid liners can be of twotypes—water-based and alcohol-based (water proof) eyeliners

Application of eyeliner

Liquid eyeliners usually come with a brush attachedto the cap. To apply, Stroke the eyeliner evenly across the lid as close to thebase of your eyelashes as possible. Look down and stay like that for a few secondsto give it time to dry and prevent smudging.
Forpencil eyeliners, carefully draw a soft line, keeping close to your upper eyelashes.You can repeat the same under your lower lashes too.

Eyeliner should be applied after eye shadow and before mascara

Eyeshadows
Eyeshadows give a soft smoky effect and are very effective in highlighting and definingyour eyes. To bring out the beauty of your eyes, you need to consider your skinand eye colors while choosing the color of an eyeshadow. The color should blendwell with your skin tone, dress and makeup. Eyeshadows come in a variety of forms—pressedpowders, cream, stick and liquid eyeshadows. Available in pearly and matt textures,pressed powders are the most popular form of eyeshadows

Application of eyeshadows

Using a small brush, apply base color to the entire lid from the outside to theinside corner and from the base of the lashes to the eyelid crease.
After that a deeper shade is blended into the crease line.
Apply a lighter shade under the brow bone area to highlight the eyes.
A light or bright shade on the lid will make your eyes appear larger, while a darktone will make your eyes appear smaller.
Avoid dark tones if you have very light skin.

Mascara
Mascara creates a flattering fringe to your eyes. It thickens and darkens the eyelashesand gives the eye makeup, the finishing touch. There are three forms of mascara:

Water-based mascara: Water-based mascaras won’t stay for a long time, as it tendsto smudge easily when it comes into contact with water or perspiration. They aregentle to your lashes and can be removed easily.Water-proof mascara: Water-proofmascaras are generally water- and smudge-proof. It takes long time to dry and difficultto remove it. You may have to use a cosmetic cleaner to remove them from your lashes.

Mixed-variety mascara: Mixed-variety mascaras are combination of water-based andwater-proof mascaras. They dry quickly, are easy to remove and produce little orno smudging

Application of mascara

Most of the mascaras are applied with spiral wands that are quick and easy to use.Start by applying mascara to your upper lashes from their base to the tips, curling them up upward with the brush.Next, use the tip of the mascara wand to brush your lower lashes, using a gentle side-to-side technique.Make sure that you keep and steady while you are applying the mascara and do not blink while the mascara is still wet. You can apply mascara again for a more defined effect.

Finally brush through your lashes with an eyelash comb to remove any excess, and to prevent your lashes from clumping.

Under eye concealers
Concealers are intended to disguise blemishes, dark circles and red veins. They are concentrated foundation with high pigment content and usually come in stick, cream and liquid forms. Choose for a concealer that looks nearest to your own skin tone.

Adverse effects of eye cosmetics

Dangerous bacteria or fungi can grow in some cosmetic products leading to certain eye infections.
A mascara wand or other applicators may cause injury to your eye by scratching the cornea. Corneal injury needs prompt medical attention.
Bacteria from the skin can grow in the cosmetic after use. Contamination of cosmetics can cause conjunctivitis, which is the infection of the outer part of the eyeball.
Preservatives in eye cosmetics can irritate the eye and skin in some people who has sensitive skin.
Permanent eyelash and eyebrow tints and dyes have been known to cause serious eye injuries.
Some people develop allergic reactions to fragrances or other ingredients in eye cosmetics. Tearing, itching, redness of the eyes, or swelling of the eyelids are some common symptoms of allergy.
Testers in retail stores and at cosmetics counters can spread germs from one person to another when eye makeups are shared.
Contact lens wearers and people with sensitive skins are more prone to eye infections and allergy.

Safety tips for using eye cosmetics

When you try out ‘testers’ at cosmetic shops, make sure the demonstrator uses only fresh applicators.
Avoid adding saliva or water to moisten eye cosmetics as it may introduce bacteria. Your saliva contains bacteria from your mouth.
Use only cosmetics intended for the eyes on the eyes. For example, never use a lip liner as eyeliner.
Never dye eyelashes and eyebrows, as they may cause serious eye injuries.
Never use an old applicator to a fresh cosmetic, as it may introduce bacteria to the new cosmetic.
Avoid using eye cosmetics if you have an infection. Discard any eye cosmetics you were using when you got the infection.
Never share eye cosmetics with others. Each person has different skin bacteria. Another person’s bacteria may contaminate your cosmetics and you may get an infection.
Never apply eye cosmetics in a moving vehicle.
Stop using cosmetics immediately if it causes any irritation.
Avoid using old eye cosmetics. Never use dried up mascara. Replace eye cosmetics for every 6 months or more often if you use contact lenses.

Consult your doctor if you think you have any cosmetic eye-related problem.