Saturday, 2 June 2012


The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite (often called TCP/IP, although not all applications use TCP) to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic, wireless and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support email.

Most traditional communications media including telephone, music, film, and television are reshaped or redefined by the Internet, giving birth to new services such as Voice over Internet Protocol (VoIP) and Internet Protocol Television (IPTV). Newspaper, book and other print publishing are adapting to Web site technology, or are reshaped into blogging and web feeds. The Internet has enabled and accelerated new forms of human interactions through instant messaging, Internet forums, and social networking. Online shopping has boomed both for major retail outlets and small artisans and traders. Business-to-business and financial services on the Internet affect supply chains across entire industries.

A Hierarchy of Networks
  • From a single computer to LAN 
  • From LAN to ISP
  • ISP to WWW
internet access Via:

 dial-up,
 landline (over coaxial cable, fiber optic or copper wires),
 T- lines,
 WiFi / WiMAX
 satellite
 GPRS, EDGE. ….
 cell phones
 3G…..

Internet protocol
  • Every machine on the Internet has a unique identifying number, called an IP Address.
  • The IP stands for Internet Protocol, which is the language that computers use to communicate over the Internet.
  • A protocol is the pre-defined way that someone who wants to use a service talks with that service. The "someone" could be a person, but more often it is a computer program like a Web browser., etc.
  • An Internet Protocol address (IP address) is a numerical label that is assigned to devices participating in a computer network that uses the Internet Protocol for communication between its nodes
  • An IP address serves two principal functions: host or network interface identification and location addressing

Internet protocol
  •  A typical IP address looks like this:
  • To make it easier for us humans to remember, IP addresses are normally expressed in decimal format as a dotted decimal number like the one above.
  • But computers communicate in binary form. Look at the same IP address in binary: 11011000.00011011.00111101.10001001
What is the meaning of ?


 TCP/IP (Internet) Applications
 World Wide Web's Hypertext Transfer Protocol (HTTP)
 Simple Mail Transfer Protocol (SMTP)
 File Transfer Protocol (FTP)
 Telnet (Telnet) which lets you logon to remote computers
 Simple Network Management Protocol (SNMP)
 VoIP

Domain Name System (DNS) The Internet naming scheme which consists of a hierarchical sequence of names, from the most specific to the most general (left to right), separated by dots : example ?
 IP (Internet protocol) The Internet standard protocol that provides a common layer over dissimilar networks, used to move packets among host computers and through gateways if necessary.
 IP Address The numeric address of a computer connected to the Internet; also called Internet address.

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