Introduction The Internet is a new communication technology that is widely used sometimes referred to as 'net'. It is not a single network but a global connected network of computers providing free exchange of information.It is similar to a peer-to-peer connectivity. The net delivers data and information from once place on earth to another. Some of the services of Internet are email, file uploading and downloading, efax, ephone services, chatting, video conferencing and other net tools. The net is accessed through a set of software called the browser. Some of the widely used browsers are Internet Explorer provided by Microsoft, Mozilla Firefox, Opera, Google Chrome, Netscape Navigator etc. Origin of Internet ARPANET is the ancestor of the Internet. It is Advanced Research Projects Administration Network. The project was an experiment in reliable networking and to link defense and military research contractors. The funds were provided by the Department of Defense [DOD]of the US in 1969. The ARPANet is now called the DARPANET. Since its popularity and the number of computers increased the DARPAnet divided into MILNet and the Internet. Networks and Different Topologies A network is a set of computers interconnected together by different transmission paths to exchange information. A network topology is the representation of the physical connection of different computers connected in the network. Some of the common topologies are 1. Star 2. Ring 3. Bus 4. Hierarchical Topology Star Topology It is a commonly used topology for data communication systems. In this topology computers are connected in a star fashion. Ring Topology In this computer are connected in a ring fashion. That is each computer is physically connected two other computers in the same network. Bus Topology In this type of network, a single station broadcasts to multiple computers. That is only one communication channel for all the devices connected to the network. Hierarchical topology This is also known as a tree network. In this computers are connected in a hierarchical fashion. One advantage of this is that we can connect any number of peripherals to this network.