Mobile Internet Many users on the Internet have portable computers and want to stay connected to the Internet when they visit a distant site away from their homes, office or even while travelling on the road. Using wireless network interfaces, mobile devices can be connected to the Internet in the same way as desktop machines are connected using ethernet, token ring or point to point links. The use of a wireless channel for data communication is not a new development. In fact the wireless technology has been in use over satellite, microwave and cordless channels for over half a century. What is new is its application for providing local and wide area Personal Communication Services.
Internet is built upon a collection of networks that cover the world.
These networks contains differnt types of computers, and somehow, something must hold the whole thing togather. Within Internet data is broken into small packets called fragments. For example, say that you send a long mail on the other side of the country. TCP will divide the message int o packets. Each packet is marked with a sequence number.