Internet

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Internet
Internet:
Publicly accessible computer network connecting many smaller networks from
around the world.
It grew out of a U.S. Defense Department program called ARPANET (Advanced
Research Projects Agency Network), established in 1969 with connections
between computers at the University of California at Los Angeles, Stanford
Research Institute, the University of California-Santa Barbara, and the University
of Utah. ARPANET's purpose was to conduct research into computer networking
in order to provide a secure and survivable communications system in case of
war. As the network quickly expanded, academics and researchers in other fields
began to use it as well. In 1971 the first program for sending e-mail over a
distributed network was developed; by 1973, the year international connections
to ARPANET were made (from Britain and Norway), e-mail represented most of
the traffic on ARPANET. The 1970s also saw the development of mailing lists,
newsgroups and bulletin-board systems, and the TCP/IP communications
protocols, which were adopted as standard protocols for ARPANET in 1982–83,
leading to the widespread use of the term Internet. In 1984 the domain name
addressing system was introduced. In 1986 the National Science Foundation
established the NSFNET, a distributed network of networks capable of handling
far greater traffic, and within a year more than 10,000 hosts were connected to
the Internet. In 1988 real-time conversation over the network became possible
with the development of Internet Relay Chat protocols . In 1990 ARPANET ceased
to exist, leaving behind the NSFNET, and the first commercial dial-up access to the
Internet became available. In 1991 the World Wide Web was released to the
public (via FTP). The Mosaic browser was released in 1993, and its popularity led
to the proliferation of World Wide Web sites and users. In 1995 the NSFNET
reverted to the role of a research network, leaving Internet traffic to be routed
through network providers rather than NSF supercomputers. That year the Web
became the most popular part of the Internet, surpassing the FTP protocols in
traffic volume. By 1997 there were more than 10 million hosts on the Internet and

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more than 1 million registered domain names. Internet access can now be gained
via radio signals, cable-television lines, satellites, and fibre-optic connections,
though most traffic still uses a part of the public telecommunications (telephone)
network. The Internet is widely regarded as a development of vast significance
that will affect nearly every aspect of human culture and commerce in ways still
only dimly discernible.
Internet service provider (ISP)
Company that provides Internet connections and services to individuals and
organizations.
For a monthly fee, ISPs provide computer users with a connection to their site, as
well as a log-in name and password. They may also provide software packages
(such as browsers), e-mail accounts, and a personal Web site or home page. ISPs
can host Web sites for businesses and can also build the Web sites themselves.
ISPs are all connected to each other through network access points, public
network facilities on the Internet backbone.
Data Transmission
Sending and receiving data via cables (e.g., telephone lines or fibre optics) or
wireless relay systems.
Because ordinary telephone circuits pass signals that fall within the frequency
range of voice communication (about 300–3,500 hertz), the high frequencies
associated with data transmission suffer a loss of amplitude and transmission
speed. Data signals must therefore be translated into a format compatible with
the signals used in telephone lines. Digital computers use a modem to transform
outgoing digital electronic data; a similar system at the receiving end translates

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the incoming signal back to the original electronic data. Specialized data-transmission
links carry signals at frequencies higher than those used by the
public telephone network.
Protocol
In computer science, a set of rules or procedures for transmitting data
between electronic devices, such as computers.
In order for computers to exchange information, there must be a preexisting
agreement as to how the information will be structured and how each side
will send and receive it. Without a protocol, a transmitting computer, for
example, could be sending its data in 8-bit packets while the receiving
computer might expect the data in 16-bit packets. Protocols are established by
international or industrywide organizations. Perhaps the most important
computer protocol is OSI (Open Systems Interconnection), a set of guidelines
for implementing networking communications between computers. The most
important sets of Internet protocols are TCP/IP, HTTP, and FTP.
Types of Protocol
FTP
In full file transfer protocol
Internet protocol that allows a computer to send files to or receive files from another
computer.
Like many Internet resources, FTP works by means of a client-server architecture; the user runs
client software to connect to a server on the Internet. On the FTP server, a program called a
daemon allows the user to download and upload files. Before the World Wide Web was
introduced, FTP was one of the most popular methods of exchanging information over the
Internet and many Web sites still use it to disseminate their larger files .
TCP/IP

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In full Transmission Control Protocol/Internet Protocol
Standard Internet communications protocols that allow digital computers to communicate over
long distances.
The Internet is a packet-switched network, in which information is broken down into small
packets, sent individually over many different routes at the same time, and then reassembled
at the receiving end. TCP is the component that collects and reassembles the packets of data,
while IP is responsible for making sure the packets are sent to the right destination. TCP/IP was
developed in the 1970s and adopted as the protocol standard for ARPANET (the predecessor to
the Internet) in 1983.
HTTP
In full HyperText Transfer Protocol
Standard application-level protocol used for exchanging files on the World Wide
Web.
HTTP runs on top of the TCP/IP protocol. Web browsers are HTTP clients that
send file requests to Web servers, which in turn handle the requests via an HTTP
service. HTTP was originally proposed in 1989 by Tim Berners-Lee, who was a
coauthor of the 1.0 specification. HTTP in its 1.0 version was “stateless”: each new
request from a client established a new connection instead of handling all similar
requests through the same connection between a specific client and server.
Version 1.1 includes persistent connections, decompression of HTML files by
client browsers, and multiple domain names sharing the same IP address.
IP Address
In full Internet Protocol address
Number that uniquely identifies each computer on the Internet.

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A computer's IP address may be permanently assigned or supplied each time that
it connects to the Internet by an Internet service provider. In order to
accommodate the extraordinary growth in the number of devices connected to
the Internet, a 32-bit protocol standard, known as IPv4, began to be replaced by a
128-bit protocol, IPv6, in 2000.
World Wide Web (WWW)
Leading information-exchange service of the Internet.
It was created by Tim Berners-Lee and his colleagues at CERN and introduced to the world in
1991. The Web gives users access to a vast array of documents that are connected to each
other by means of hypertext or hyperlinks. A hypertext document with its corresponding text
and hyperlinks is written in HTML and is assigned an on-line address, or URL. The Web operates
within the Internet's basic client-server architecture. Individual HTML files with unique
electronic addresses are called Web pages, and a collection of Web pages and related files
(such as graphics files, scripted programs, and other resources) sharing a set of similar
addresses (see domain name) is called a Web site. The main or introductory page of a Web site
is usually called the site's home page. Users may access any page by typing in the appropriate
address, search for pages related to a topic of interest by using a search engine, or move quickly
between pages by clicking on hyperlinks incorporated into them. Though introduced in 1991,
the Web did not become truly popular until the introduction of Mosaic, a browser with a
graphical interface, in 1993. Subsequently, browsers produced by Netscape and Microsoft have
become predominant.
Internet Tools
The following are the some popular internet tools.
1. FTP (File Transfer Protocol)
2. Newsreader
3. Telnet
4. Videoconferencing

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URL :
In full Uniform Resource Locator
Address of a resource on the Internet.
The resource can be any type of file stored on a server, such as a Web page, a text file, a
graphics file, or an application program. The address contains three elements: the type of
protocol used to access the file (e.g., HTTP for a Web page, ftp for an FTP site); the domain
name or IP address of the server where the file resides; and, optionally, the pathname to the
file (i.e., description of the file's location). For example, the URL .
Browser :
Software that allows a computer user to find and view information on the
Internet.
The first text-based browser for the World Wide Web became available in
1991; Web use expanded rapidly after the release in 1993 of a browser called
Mosaic, which used “point-and-click” graphical manipulations. Such Web
browsers interpret the HTML tags in downloaded documents and format the
displayed data according to a set of standard style rules. Netscape Navigator
became the dominant Web browser soon after its release in 1994; Microsoft's
Internet Explorer was introduced a year later and has become widespread.
Domain Name :
Address of a computer, organization, or other entity on a TCP/IP network such as
the Internet.
Domain names are typically in a three-level “server.organization.type” format.
The top level denotes the type of organization, such as “com” (for commercial
sites) or “edu” (for educational sites); the second level is the top level plus the

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name of the organization (e.g., “britannica.com” for Encyclopædia Britannica);
and the third level identifies a specific host server at the address, such as the
“www” (World Wide Web) host server for “www.britannica.com”. A domain
name is ultimately mapped to an IP address, but two or more domain names can
be mapped to the same IP address. A domain name must be unique on the
Internet, and must be assigned by a registrar accredited by the Internet
Corporation for Assigned Names and Numbers (ICANN).