Copyright Goodheart-Willcox Co., Inc. Chapter 1 Introduction to Information Technology 17 Internet The Internet is a worldwide communication network that connects individual computer networks. Messages are exchanged between these networks, and then the destination network must deliver the message to the correct computer in its network. It sounds complicated, but the process is very simple to understand. The routing mechanism is based on small fi le fragments called packets. The transmission control protocol (TCP) identifi es a fi le to be sent and breaks it into packets, each of which is given a header. The packet header contains the: • fi le’s source computer’s Internet protocol (IP) address, which uniquely identifi es each computer on a network • destination computer’s IP address • packet number and • total number of packets in the entire fi le. These packets are sent though the network of networked computers, possibly not on the same path, as shown in Figure 1-12. World Wide Web The World Wide Web (WWW) is a subset of the Internet that consists of a collection of documents connected by uniform resource locator (URL) codes and hypertext protocol, as illustrated in Figure 1-13. Computer A Packet Switch Packet Switch Packet Switch Computer B Computer C Computer D Packet Switch Packet Switch Packet Switch Packet Switch To C T o C To C T o C T o D To D To D To D To D To D To C Goodheart-Willcox Publisher Macrovector/Shutterstock.com Figure 1-12. The TCP breaks a file into packets, which are then sent through the network.