McAfee 5 manual Why packets?, Internet and the Web…what is the difference?

Internet Security and Privacy

Why packets?

Why go through all this trouble, breaking data down into packets? The answer lies in the origins of TCP/IP. Like the Internet itself, it is a product of the Cold War. The United States Department of Defense originally developed the Internet. It was designed to ensure secure communications, even with multiple communications network failures anticipated in the event of a nuclear war. TCP/IP solves the problem of network failure by assuming that a certain amount of noise always exists in the network— noise referring either to random data errors or more serious system crashes. If you have ever tried to speak in a noisy room, you know the necessity of repeating yourself—and that is exactly what TCP/IP is designed to do. Breaking the data down into packets allows the Internet to seek alternate routes if one route is inaccessible. If a packet cannot get through or arrives damaged, the receiving computer simply requests it again until it arrives successfully.

When you send an e-mail message, for example, it is broken into several packets. Depending on how noisy the network is, each packet may need to be routed over a separate route in order to find its way to its destination. Furthermore, network problems may cause some of the packets to be delayed so they arrive out of order. To compensate, TCP examines each packet as it arrives to verify that it's OK. Once all the packets are received, TCP puts them back in their original order. Of course, all of this happens quickly and automatically, so you will never see the process at work.

The Internet and the Web…what is the difference?

Before the Web, the Internet was mostly command-line driven and character-based— you had to type in the exact Internet address of the place you wanted to go at a command line. In 1989, Tim Berners-Lee of the European Particle Physics Laboratory proposed a new way to share information over the Internet. The essential feature in Berner-Lee’s vision of the Web is that it links documents together. When you click a link on a Web page, you are automatically connected to another Web site. This linking function, combined with the increasing graphics abilities of home computers, transformed the Internet into a graphically rich place, complete with video, sound, and pictures. Through the linking of information together in a graphically appealing package, the Web made the Internet more attractive to the typical consumer.

The Internet is a network of linked computers that uses TCP/IP as its underlying messaging system. The World Wide Web (WWW, or just “Web” for short) is hosted by the Internet, and is an ever-expanding collection of documents employing a special coding scheme named Hypertext Markup Language (HTML).

HTML is a set of commands designed to be interpreted by Web browsers. An HTML document consists of content (prose, graphics, video, etc.) and a series of commands that tell a Web browser how to display the content.

100 McAfee Internet Security 5.0