No part of this may be reproduced, stored in a retrieval system, or transcribed without permission of the publisher. Each site on the Internet has a unique numeric address called its IP address and usually a corresponding name called the domain name.
Information is passed around the Internet in packets.
Each packet contains the address of the sender and the address of the destination. The packets can take different paths through the Internet. It's up to the software at the destination to receive the packets and reassemble them. The emphasis is placed on the packets, not on the connections between systems. A program called the client is started on one system and contacts a program called the server at another computer on the Internet.