The Internet is the worldwide, publicly accessible network of interconnected computer networks that transmit data using the standard Internet Protocol (IP). Contrary to some common usage, the Internet and the World Wide Web are not synonymous: the Internet is a collection of interconnected computer networks while the Web is a collection of interconnected documents. The World Wide Web is accessible via the Internet.

The Internet Protocol (IP) is a data-oriented protocol used for communicating data across the Internet.

Internet Protocol version 4 (IPv4) is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed.

Internet Protocol version 6 (IPv6) is an IP standard used by electronic devices to exchange data across a network. It follows IPv4 as the second version of the Internet Protocol to be formally adopted for general use.

The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. The protocol guarantees reliable and in-order delivery of data from sender to receiver. TCP supports many of the Internet’s most popular application protocols and resulting applications, including the World Wide Web and e-mail.

A webpage is a resource of information that is suitable for the World Wide Web and can be accessed through a web browser. This information is usually in HTML or XHTML format, and may provide navigation to other web pages via hypertext links.

A web browser is a software that enables a user to display and interact with text, images, and other information typically located on a web page at a website on the World Wide Web or a local area network. Text and images on a web page can contain hyperlinks to other web pages at the same or different websites. Web browsers allow a user to quickly and easily access information provided on many web pages at many websites by traversing these links.

Web browsers available for personal computers include Microsoft Internet Explorer, Mozilla Firefox, Apple Safari, Netscape, and Opera, in order of descending popularity (as of August 2006). ViolaWWW, first developed in the early 1990s, was the first popular web browser (though to a limited audience) which until Mosaic, was the most frequently used for access to the World Wide Web.

The World Wide Web (“WWW” or simply the “Web“) is a global, read-write information space. Text documents, images, multimedia and many other items of information, referred to as resources, are identified by short, unique, global identifiers called Uniform Resource Identifiers (URIs) so that each can be found, accessed and cross-referenced in the simplest possible way.

The term is often mistakenly used as a synonym for the Internet itself, but the Web is actually something that is available via the Internet, just like e-mail and many other Internet services.

The underlying ideas of the Web can be traced as far back as 1980, when Tim Berners-Lee built ENQUIRE (referring to Enquire Within Upon Everything, a book he recalled from his youth). While it was rather different from the Web we use today, it contained many of the same core ideas.

Internet2 or UCAID (University Corporation for Advanced Internet Development) is a non-profit consortium which develops and deploys advanced network applications and technologies, mostly for high-speed data transfer.

A hyperlink (often referred to as simply a link), is a reference in a document to another document (in the WWW), that automatically brings the referred information to the user when the navigation element is selected (by clicking) by the user. Hyperlinks are part of the foundation of the World Wide Web created by Tim Berners-Lee.

A Uniform Resource Locator (URL) is a widespread synonym for Uniform Resource Identifier (URI). It is used to identify a resource (a webpage, for example) on the WWW. A hyperlink is a URL.

An IP address (Internet Protocol address) is a unique number that devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP). Any participating network device — including routers, computers, time-servers, printers, Internet fax machines, and some telephones — must have its own unique address. An IP address can also be thought of as the equivalent of a street address or a phone number for a computer or other network device on the internet. Just as each street address and phone number uniquely identifies a building or telephone, an IP address can uniquely identify a specific computer or other network device on a network.A network lookup service, the Domain Name System (DNS), provides the ability to map hostnames to an IP address. This allows humans to easily remember a name and not a series of numbers. DNS allows multiple addresses and names to point to one Internet resource.

For example, www.wikipedia.org resolves to 207.142.131.248.

Note: 207.142.131.248 is both Wikipedia and Wikimedia. The web browser sends the desired hostname as a part of the request, allowing the web server to present the appropriate page.

IPv4 uses 32-bit (4 byte) addresses, which limits the address space to 4,294,967,296 (2³²) possible unique addresses. The numerical limitation of the number of addresses possible with a 32-byte address has helped stimulate the push towards IPv6, which is currently in the early stages of deployment and is currently the only contender to replace IPv4.

In IPv6, the new (but not yet widely deployed) standard protocol for the Internet, addresses are 128 bits wide, which, even with generous assignment of netblocks, should suffice for the foreseeable future. In theory, there would be exactly 2¹²⁸, or about 3.403 × 10³⁸ unique host interface addresses. The exact number is 340,282,366,920,938,463,463,374,607,431,768,211,456. This large address space will be sparsely populated, which makes it possible to again encode more routing information into the addresses themselves.

This magnitude of IPs available will be necessary in the future as mobile phones, cars and all types of personal devices come to rely on the internet for everyday purposes.

ICANN (pronounced “I can”) is the Internet Corporation for Assigned Names and Numbers. Headquartered in Marina Del Rey, California, ICANN is a California non-profit corporation that was created on September 18, 1998 in order to oversee a number of Internet-related tasks previously performed directly on behalf of the U.S. Government by other organizations, notably IANA.

The tasks of ICANN include managing the assignment of domain names and IP addresses.The Internet Assigned Numbers Authority (IANA) is the entity that oversees global IP address allocation, DNS root zone management, and other Internet protocol assignments. It is operated by ICANN.

The Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the United States Department of Defense was the progenitor of the global Internet.

The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet and most commercial networks run. It is sometimes called the TCP/IP protocol suite, after the two most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were also the first two defined.

Sir Timothy John “Tim” Berners-Lee, KBE (born June 8, 1955 in London, England) is the inventor of the World Wide Web and director of the World Wide Web Consortium, which oversees its continued development. Informally, in technical circles, he is sometimes called “TimBL” or “TBL”.

The World Wide Web Consortium (W3C) is an international consortium where member organizations, a full-time staff and the public work together to develop standards for the World Wide Web.

A firewall is a piece of hardware and/or software which functions in a networked environment to prevent some communications forbidden by the security policy, analogous to the function of firewalls in building construction.

HyperText Markup Language (HTML) is a predominant markup language for the creation of web pages.

The Extensible HyperText Markup Language, or XHTML, is a markup language that has the same expressive possibilities as HTML, but a stricter syntax.

The Extensible Markup Language (XML) is a W3C-recommended general-purpose markup language for creating special-purpose markup languages, capable of describing many different kinds of data. In other words, XML is a way of describing data.

WYSIWYG (pronounced /wɪziwɪg/, transcripted wizziwig), is an acronym for What You See Is What You Get, used in computing to describe a system in which content during editing appears very similar to the final product. It is commonly used for word processors, but has other applications, such as Web (HTML) authoring.

JavaScript is a scripting programming language based on the concept of prototypes. The language is best known for its use in websites, but is also used to enable scripting access to objects embedded in other applications. Despite the name, JavaScript is only distantly related to the Java programming language, the main similarity being their common debt to the C programming language syntax. JavaScript is a registered trademark of Sun Microsystems, Inc., used under license for technology invented and implemented by Netscape.

Hypertext Transfer Protocol (HTTP) is a method used to transfer or convey information on the World Wide Web. Its original purpose was to provide a way to publish and retrieve HTML pages.

The Hyper Text Transport Protocol - Secure (HTTPS), is a standard encrypted communication mechanism on the World Wide Web.

FTP or file transfer protocol is a commonly used protocol for exchanging files over any network that supports the TCP/IP protocol (such as the Internet or an intranet). There are two computers involved in an FTP transfer: a server and a client. The FTP server, running FTP server software, listens on the network for connection requests from other computers. The client computer, running FTP client software, initiates a connection to the server. Once connected, the client can do a number of file manipulation operations such as uploading files to the server, download files from the server, rename or delete files on the server and so on.

The Internet Message Access Protocol (commonly known as IMAP or IMAP4, and previously called Internet Mail Access Protocol) is an Internet protocol that allows a client to access e-mail on a remote server.

Lightweight Directory Access Protocol, or LDAP (“ell-dap”), is a networking protocol for querying and modifying directory services running over TCP/IP.

Electronic mail (abbreviated “e-mail” or, more commonly, “email“) is a store and forward method of composing, sending, storing, and receiving messages over electronic communication systems. The term “e-mail” (as a noun or verb) applies both to the Internet e-mail system based on the Simple Mail Transfer Protocol (SMTP) and to intranet systems allowing users within one organization to e-mail each other. Often these workgroup collaboration organizations may use the Internet protocols for internal e-mail service.

An e-mail client, also called a mail user agent (MUA), is a computer program that is used to read and send e-mail. For ex., Microsoft Outlook and Mozilla Thunderbird.

Simple Mail Transfer Protocol (SMTP) is the de facto standard for e-mail transmissions across the Internet. Extended SMTP (ESMTP) is in use today.

Post Office Protocol version 3 (POP3), is an Internet protocol, to retrieve e-mail from a remote server over a TCP/IP connection. Nearly all subscribers to individual Internet service provider e-mail accounts access their e-mail with client software that uses POP3.

The Network News Transfer Protocol or NNTP is an Internet application protocol used primarily for reading and posting Usenet articles, as well as transferring news among news servers.

A web feed is a data format used for serving users frequently updated content. Content distributers ’syndicate’ a web feed, thereby allowing users to ’subscribe’ to it. Making a collecting of web feeds accessible in one spot is known as ‘aggregation’.

RSS is a family of web feed formats. The initialism “RSS” is variously used to refer to the following standards:

• Really Simple Syndication (RSS 2.0)
• Rich Site Summary (RSS 0.91, RSS 1.0)
• RDF Site Summary (RSS 0.9 and 1.0)

RSS formats are specified in XML (a generic specification for data formats). RSS delivers its information as an XML file called an “RSS feed”, “webfeed”, “RSS stream”, or “RSS channel”.

The name Atom applies to a pair of related standards. The Atom Syndication Format is an XML language used for web feeds, while the Atom Publishing Protocol (APP for short) is a simple HTTP-based protocol for creating and updating Web resources.

Web feeds allow software programs to check for updates published on a web site. To provide a web feed, a site owner may use specialized software (such as a content management system) that publishes a list (or “feed”) of recent articles or content in a standardized, machine-readable format. The feed can then be downloaded by web sites that syndicate content from the feed, or by feed reader programs that allow Internet users to subscribe to feeds and view their content.

A feed contains entries, which may be headlines, full-text articles, excerpts, summaries, and/or links to content on a web site, along with various metadata.

The development of Atom was motivated by the existence of many incompatible versions of the RSS syndication format, all of which had shortcomings, and the poor interoperability [1] of XML-RPC-based publishing protocols. The Atom syndication format was published as an IETF “proposed standard” in RFC 4287. The Atom Publishing Protocol is still in draft form.

Podcasting is the method of distributing multimedia files, such as audio or video programs, over the Internet using syndication feeds, for playback on mobile devices and personal computers. The term, coined in 2004, is a blend of the terms “iPod”, a popular portable audio device, and “broadcasting.”

The term podcast, like ‘radio’, can mean both the content and the method of delivery. The host or author of a podcast is often called a podcaster. Though podcasters’ web sites may also offer direct download or streaming of their content, a podcast is distinguished from other formats by its ability to be downloaded automatically using software capable of reading feeds like RSS or Atom.

Usually a podcast features one type of ’show’, with new episodes released either sporadically or at planned intervals such as daily or weekly. In addition, there are podcast networks that feature multiple shows on the same feed.

A blogcast is a portmanteau of two better known media types, the blog and the podcast into a single website.

An MMS podcast is a podcast show distributed via the Multimedia Messaging Service (MMS) protocol to mobile phones. The content makes use of MMS features such as being split into random-access chapters. The shows can be fetched on demand by the user, or pushed to the user on a subscription basis.

The iPod is a brand of portable media players designed and marketed by Apple Computer. The iPod is currently the world’s best-selling digital audio player, and its worldwide mainstream adoption makes it one of the most popular consumer brands.

Streaming media is media that is consumed (heard or viewed) (mostly in the form of clips) while it is being delivered. Streaming is more a property of the delivery system than the media itself. The distinction is usually applied to media that are distributed over computer networks; most other delivery systems are either inherently streaming (radio, television) or inherently non-streaming (books, video cassettes, audio CDs). The word “stream” is also used as a verb, meaning to deliver streaming media.

Phishing is a criminal activity using social engineering techniques. Phishers attempt to fraudulently acquire sensitive information, such as passwords and credit card details, by masquerading as a trustworthy person or business in an electronic communication. Phishing is typically carried out using email or an instant message, although phone contact has been used as well.

Vishing is the practice of leveraging Voice over Internet Protocol (VoIP) technology to trick private personal and financial information from the public for the purpose of financial reward. The term is a combination of “voice” and phishing.

Pharming is a hacker’s attack aiming to redirect a website’s traffic to another (bogus) website.

Malware is software designed to infiltrate or damage a computer system, without the owner’s informed consent. It includes computer viruses, worms, Trojan horses, spyware, adware, and other malicious and unwanted software. Malware should not be confused with defective software, that is, software which has a legitimate purpose but contains harmful bugs.

Computer virus is a self-replicating computer program that spreads by inserting copies of itself into other executable code or documents. A computer virus behaves in a way similar to a biological virus, which spreads by inserting itself into living cells. Extending the analogy, the insertion of a virus into the program is termed as an “infection”, and the infected file, or executable code that is not part of a file, is called a “host”. Viruses are one of the several types of malicious software or malware.

A computer worm is a self-replicating computer program. It uses a network to send copies of itself to other systems and it may do so without any user intervention. Unlike a virus, it does not need to attach itself to an existing program. Worms always harm the network (if only by consuming bandwidth), whereas viruses always infect or corrupt files on a targeted computer.

In the context of computer software, a Trojan horse is a malicious program that is disguised as or embedded within legitimate software. The term is derived from the classical myth of the Trojan Horse. They may look useful or interesting (or at the very least harmless) to an unsuspecting user, but are actually harmful when executed.

Spyware refers to a broad category of malicious software designed to intercept or take partial control of a computer’s operation without the informed consent of that machine’s owner or legitimate user. While the term taken literally suggests software that surreptitiously monitors the user, it has come to refer more broadly to software that subverts the computer’s operation for the benefit of a third party.

Adware is any software package with the sole purpose to automatically play, display, or download advertising material to a computer after the software is installed on it. This should not be confused with advertising-supported software which is not malicious, but displays ads within its windows while the program is being used.

Spamming is the abuse of electronic messaging systems to send unsolicited, undesired bulk messages. While the most widely recognized form of spam is e-mail spam, the term is applied to similar abuses in other media: instant messaging spam, Usenet newsgroup spam, Web search engine spam, spam in blogs, and mobile phone messaging spam.

A black hat (also called a cracker or Darkside hacker) is a malicious or criminal hacker.

Cryptovirology is a field that studies how to use cryptography to design powerful malicious software. It encompasses overt attacks such as cryptoviral extortion where a cryptovirus, cryptoworm, or cryptotrojan hybrid encrypts the victim’s files and the user must pay the malware author to receive the needed session key (that is encrypted under the author’s public key that is contained in the malware).

File sharing is the practice of making files available for other users to download over the Internet and smaller networks. Usually file sharing follows the peer-to-peer (P2P) model, where the files are stored on and served by personal computers of the users. Most people who engage in file sharing are also downloading files that other users share. Sometimes these two activities are linked together. P2P File sharing is distinct from file trading in that downloading files from a P2P network does not require uploading, although some networks either provide incentives for uploading such as credits or force the sharing of files being currently downloaded.

A peer-to-peer (or P2P) computer network is a network that relies primarily on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively low number of servers. P2P networks are typically used for connecting nodes via largely ad hoc connections. Such networks are useful for many purposes. Sharing content files (see file sharing) containing audio, video, data or anything in digital format is very common, and realtime data, such as telephony traffic, is also passed using P2P technology.

MPEG-1 Audio Layer 3, more commonly referred to as MP3, is a popular digital audio encoding and lossy compression format, designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. It was invented by a team of European engineers who worked in the framework of the EUREKA 147 DAB digital radio research program, and it became an ISO/IEC standard in 1991.

The Moving Picture Experts Group or MPEG is a working group of ISO/IEC charged with the development of video and audio encoding standards.

The name JPEG stands for Joint Photographic Experts Group, the name of the joint ISO/CCITT committee that developed the JPEG standard. JPEG is a commonly used standard method of compression for photographic images. The file format which employs this compression is commonly also called JPEG; the most common file extensions for this format are .jpeg, .jfif, .jpg, .JPG, or .JPE although .jpg is the most common on all platforms.

Tagged Image File Format (abbreviated TIFF) is a file format for mainly storing images, including photographs and line art.

JNG is a JPEG-based graphics file format. The name stands for JPEG Network Graphics.

PNG (Portable Network Graphics) is a bitmap image format that employs lossless data compression. PNG was created to both improve upon and replace the GIF format with an image file format that does not require a patent license to use.

GIF (Graphics Interchange Format) is a bitmap image format using a pallete of up to 256 distinct colors from the 24-bit RGB color space. The format was introduced by CompuServe in 1987 and has since come into widespread usage on the World Wide Web due to its wide support and portability. It also supports animiations and even allows a separate pallete of 256 colors for each frame.

.BMP or .DIB (device-independent bitmap) is a bitmapped graphics format used internally by the Microsoft Windows graphics subsystem (GDI), and used commonly as a simple graphics file format on that platform.

A raster graphics image, digital image, or bitmap, is a data file or structure representing a generally rectangular grid of pixels, or points of color, on a computer monitor, paper, or other display device.

Unicode is an industry standard designed to allow text and symbols from all of the writing systems of the world to be consistently represented and manipulated by computers.

Cyberslacking is the practice of employees using the Internet or other employer-provided resources for leisure during work hours, contributing to inefficiency. Some estimate cyberslacking costs employers $1 billion a year in computer resources

Electronic commerce, EC, e-commerce or ecommerce consists primarily of the distributing, buying, selling, marketing, and servicing of products or services over electronic systems such as the Internet and other computer networks.

The Internet Society or ISOC is an international organization that promotes Internet use and access. It states that its mission is “to assure the open development, evolution and use of the Internet for the benefit of all people throughout the world.” Its members are both individuals (for whom membership is currently free–membership is open to anyone), and also corporations, organizations, governments, and universities.

Remote Access: An office worker away from his desk, perhaps the other side of the world on a business trip or a holiday, can open a remote desktop session into his normal office PC using a secure Virtual Private Network (VPN) connection via the Internet. This gives him complete access to all his normal files and data, including e-mail and other applications, while he is away.

Virtual Private Network (VPN) is a private communications network often used within a company, or by several companies or organizations or even individuals, to communicate confidentially over a publicly accessible network.

An Internet service provider (abbr. ISP, also called Internet access provider or IAP) is a business or organization that sells to consumers access to the Internet and related services.

Dial-up access is a form of Internet access through which the client uses a modem connected to a computer and a telephone line to obtain Internet access from the Internet service provider’s (ISP).

A modem (actually MODEM – modulate/demodulate) is a device that modulates a signal to encode digital information, and also demodulates the same kind of signal to decode the transmitted information.

Bits per second (bps)/Kilobits per second (Kbps)/Megabits per second (Mbps)/Gigabits per second (Gbps) indicate the speed of transmission of information.

Kilobit = 1024 bits.

Megabit = 1024 Kilobits.

Gigabit = 1024 Megabits.

Broadband Internet access, often shortened to “broadband Internet” or just “broadband“, is a high speed-/high data-transmission rate internet connection.

DSL or xDSL, is a family of technologies that provide digital data transmission over the wires of a local telephone network. DSL originally stood for Digital Subscriber Loop, although in recent years, many have adopted Digital Subscriber Line as a more marketing-friendly term for the most popular version of DSL, ADSL over UNE.

Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional modem can provide. It does this by utilizing frequencies that are normally not used by a voice telephone call, in particular, frequencies higher than normal human hearing.

The main difference between ADSL and Symmetric Digital Subscriber Line (SDSL) is that SDSL has the same upstream data transfer rate as downstream (symmetrical), whereas ADSL always has smaller upstream bandwidth (asymmetrical).
A cable modem is a unique type of modem that is designed to modulate a data signal over cable television infrastructure. Cable modems are primarily used to deliver broadband Internet access, taking advantage of unused bandwidth on a cable television network.

Satellite Internet services are used in locations where terrestrial Internet access is not available and in locations which move frequently. Internet access via satellite is available worldwide, including vessels at sea.

An Internet point of presence (PoP) is an access point to the Internet. It is a physical location that houses servers, routers, ATM switches and digital/analog call aggregators.

In computer networking, Quality of Service (QoS) refers to the probability of the telecommunication network meeting a given traffic contract. In the field of telephony, telephony quality of service refers to lack of noise and tones on the circuit, appropriate loudness levels etc., and includes grade of service.

A local area network (LAN) is a computer network covering a local area, like a home, office, or group of buildings. The defining characteristics of LANs in contrast to WANs (wide area networks) are: their much higher data rates; smaller geographic range; and that they do not require leased telecommunication lines.

A wide area network or WAN is a computer network covering a broad geographical area. Contrast with personal area networks (PANs), metropolitan area networks (MANs) or local area networks (LANs) that are usually limited to a room, building or campus. The most well-known example of a WAN is the Internet.

A wireless LAN or WLAN is a wireless local area network, which is the linking of two or more computers without using wires. It uses radio communication to accomplish the same functionality that a wired LAN has.

Wi-Fi, also, WiFi, Wi-fi or wifi, is a brand originally licensed by the Wi-Fi Alliance to describe the underlying technology of wireless local area networks (WLAN) based on the IEEE 802.11 specifications.

Wi-Fi was developed to be used for mobile computing devices, such as laptops, in LANs, but is now increasingly used for more applications, including Internet and VoIP phone access, gaming, and basic connectivity of consumer electronics such as televisions and DVD players, or digital cameras. There are even more standards in development that will allow Wi-Fi to be used by cars in highways in support of an Intelligent Transportation System to increase safety, gather statistics, and enable mobile commerce IEEE 802.11p.

A person with a Wi-Fi device, such as a computer, telephone, or personal digital assistant (PDA) can connect to the Internet when in proximity of an access point. The region covered by one or several access points is called a hotspot.

Wi-Fi also allows connectivity in peer-to-peer mode, which enables devices to connect directly with each other. This connectivity mode is useful in consumer electronics and gaming applications.

When the technology was first commercialized there were many problems because consumers could not be sure that products from different vendors would work together. The Wi-Fi Alliance began as a community to solve this issue so as to address the needs of the end user and allow the technology to mature. The Alliance created another brand “Wi-Fi CERTIFIED” to denote products are interoperable with other products displaying the “Wi-Fi CERTIFIED” brand.

Advantages of Wi-Fi

• Allows LANs to be deployed without cabling, typically reducing the costs of network deployment and expansion.
• Spaces where cables cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.
• Wi-Fi silicon pricing continues to come down, making Wi-Fi a very economical networking option and driving inclusion of Wi-Fi in an ever-widening array of devices.
• Wi-Fi products are widely available in the market. Different brands of access points and client network interfaces are interoperable at a basic level of service. Products designated as Wi-Fi CERTIFIED by the Wi-Fi Alliance are interoperable and include WPA2 security.
• Wi-Fi networks support roaming, in which a mobile client station such as a laptop computer can move from one access point to another as the user moves around a building or area.
• Wi-Fi is a global set of standards. Unlike cellular carriers, the same Wi-Fi client works in different countries around the world.
• Widely available in more than 250,000 public hot spots and millions of homes and corporate and university campuses worldwide.
• As of 2006, WPA and WPA2 encryption are not easily crackable if strong passwords are used
• New protocols for Quality of Service (WMM) and power saving mechanisms (WMM Power Save) make Wi-Fi even more suitable for latency-sensitive applications (such as voice and video) and small form-factor devices.

Disadvantages of Wi-Fi

• Spectrum assignments and operational limitations are not consistent worldwide
• Power consumption is fairly high compared to some other standards, making battery life and heat a concern.
• The most common wireless encryption standard, Wired Equivalent Privacy or WEP, has been shown to be breakable even when correctly configured.
• Congestion.
• Wi-Fi networks have limited range. A typical Wi-Fi home router using 802.11b or 802.11g might have a range of 45 m (150 ft) indoors and 90 m (300 ft) outdoors.
• Wi-Fi pollution, meaning interference of a closed or encrypted access point with other open access points in the area, especially on the same or neighboring channel, can prevent access and interfere with the use of other open access points by others caused by overlapping channels in the 802.11g/b spectrum as well as with decreased signal-to-noise ratio (SNR) between access points. This is a widespread problem in high-density areas such as large apartment complexes or office buildings with many Wi-Fi access points.
• It is also an issue when municipalities or other large entities such as universities seek to provide large area coverage. Everyone is considered equal when they use the band (except for amateur radio operators who are the primary licensee); often this causes contention when one user seeks to claim priority in this unlicensed band. This openness is also important to the success and widespread use of Wi-Fi, but makes Part 15 (US) unsuitable for “must have” public service functions.
• Wi-Fi networks can be monitored and used to read and copy data (including personal information) transmitted over the network when no encryption such as VPN is used.
• Interoperability issues between brands or deviations from the standard can disrupt connections or lower throughput speeds on other user’s devices within range. Wi-Fi Alliance programs test devices for interoperability and designate devices which pass testing as Wi-Fi CERTIFIED.

WiMAX is defined as Worldwide Interoperability for Microwave Access by the WiMAX Forum, formed in April 2001 to promote conformance and interoperability of the IEEE 802.16 standard, officially known as WirelessMAN. The Forum describes WiMAX as “a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL”.

Uses of WiMAX:

The bandwidth and reach of WiMAX make it suitable for the following potential applications:

• Connecting Wi-Fi hotspots with each other and to other parts of the Internet
• Providing a wireless alternative to cable and DSL for last mile (last km) broadband access.
• Providing high-speed mobile data and telecommunications services (4G)

Broadband Access – Many cable and traditional telephone companies are closely examining or actively trialling the potential of WiMAX for “last mile” connectivity. This could result in better price-points for both home and business customers as based on the benefits of competition. In areas without pre-existing physical cable or telephone networks, WiMAX could allow broadband access that has hitherto been unavailable. Home units the size of a paperback book that provide both phone and network connection points are already available and easy to install.

Mobile Applications – There is potential for using WiMAX with legacy cellular networks. WiMAX antennas can “share” a cell tower without compromising the function of cellular arrays already in place. In line with these possible applications is the technology’s ability to serve as a high bandwidth “backhaul” for Internet or cellular phone traffic from remote areas back to an internet backbone.

Given the limited wired infrastructure in some developing countries, the costs to install a WiMAX station in conjunction with an existing cellular tower or even as a solitary hub are likely to be small in comparison to developing a wired solution.

Areas of low population density and flat terrain are particularily suited to WiMAX and its range.

For countries that have skipped wired infrastructure as a result of inhibitive costs and unsympathetic geography, WiMAX can enhance wireless infrastructure in an inexpensive, decentralized, deployment-friendly and effective manner.

Wi-Fi and WiMAX – Wi-Fi is a Wireless Local Area Network (LAN) technology that works in unlicensed spectrum, using the 2.4GHz and 5 GHz bands. Wi-Fi is a cheap and easy way of providing local connectivity at high speed. WiMAX uses licenced spectrum and has strong authentication mechanisms built in. It has considerably greater range than Wi-Fi. Taken together, this means that WiMAX and Wi-Fi are generally complementary rather than competing.