Internet is a global connection of computers which are linked together by cables and telephone line making communication possible among them. It is a word wide network of computers. The main role of a network is to transfer data between 2 computers. For such communication we require :
* The address of the destination.
* A safe means of moving data in the form of electric signals. For the safe movement of data, there is a set of rules which govern the sending and receiving of data on the Internet.
# Internet is a packet switching network. The data to be transmitted, is converted into small packets. The software which is responsible for making the internet function efficiently is TCP/IP.
(a) TCP – It stands for Transmission Control Protocol. It breaks up the data to be sent into little packets. It guarantees that, any data sent to the destination computer reaches intact. It makes the process appear as if one computer is directly connected to the other.
(b) IP – Internet Protocol is a set of conventions used to pass packets from one host to another. It is responsible for routine the packets to the desired destination using IP address. Packets are passed using various mechanism : repeaters, bridges, routers and gateways. The type of source and destination networks decides the mechanism to be used.
# Internet Services -
Internet provides many tools which can be used to harness the power of it s gloval resources. Most of these are menu driven or hypertext documents to guide the user through these resources.
(a) MOSAIC – It is a GUI browser developed by National center of super computing applications (NCSA), Illinois. This browser can be used on X-Windows, MS-Windows, SUN system, and many other operating systems. Mosaic, A hypermedia system, provides a unified hypermedia interface for data formats and protocols used on the internet.
(b) ARCHIE – It is a search program which helps the users to locate files and directories on anonymous FTP server anywhere on the internet. It responds to queries based on complete or partial file names. Archie runs as a client program allows us To retrieve Public domain files. These files can be text based, graphic based or sound files. The Archie database can be accessed through a local client, an interactive Telnet session or through electronic mail.
(c) GOPHER – It is a document retrieval system. It was developed at university of Minnesota in 1991. The internet offers the Gopher space. Gopher allows us, to gather information from across the internet that could be in the form of text, images and sound or services in the form of Telnet connection.
(d) USENET – Also known as Net news, is a public network made up of thousands of news groups. A news group is a collection of message With a related topic or a theme such as seminars, conferences etc. The Usenet is many to many conversation. The messages are floated in the network through a protocol called NNTP.
(e) WAIS – Wide Area Information Services is a network information retrieval system. The search is based on the keywords provided. WAIS keeps track that, how many times the keyword is found in documents.
(f) WWW – World Wide Web is a graphical and user friendly interface to the internet. It is a series of servers that are interconnected through hypertext. Hypertext is one method of presenting information in which certain items are highlighted. By selecting the highlighted text, we can obtain more information on the same topic. The internet knows the servers by their addresses. The web offers another service a URL (Uniform Resource Locator) which defines a universal locator mechanism for data resident anywhere on the net.
# E-mail –
One of the important service of Internet is Electronic mail i.e. E-mail. In this technique, the messages, voices or data are passed through telecommunications. This is a very beneficial parameter of information technology. It saves both, paper work and time to a large extent. A number of copies of the message can be flashed to a number of receivers. A message is stored if the receiver is not available. He can retrieve a message as per his convenience, the output i.e. message can be obtained in printed form as well.