Internet

The Internet is a worldwide network of computer networks built on common standards. Created in the late 1960s, it has grown into the world's largest network, with more than 1 billion Internet hosts in over 245 countries by 2016.

Three extremely important concepts form the basis for understanding the Internet: packet switching, the TCP/IP communications protocol, and client/server computing. Packet switching is a method of slicing digital messages into discrete units called packets, sending them along different communication paths as they become available, and reassembling the packets once they arrive at their destination.

Transmission Control Protocol/Internet Protocol (TCP/IP) is the core communications protocol for the Internet. TCP establishes connections among sending and receiving computers and makes sure packets arrive in sequence; IP provides the Internet's addressing scheme and is responsible for the actual delivery of packets.

Client/server computing is a model in which client computers are connected in a network with one or more servers. The Internet is a giant example of client/server computing, in which millions of web servers located around the world can be easily accessed by millions of client computers.