TCP/IP (Transmission Control Protocol/Internet Protocol) is technology that allows computers and operating systems of all kinds to communicate with one another, and it forms the basis of the Internet and intranets. TCP/IP allows any connected host to talk to any other connected without knowing anything about them or the pathways between them. This text provides an introduction to what TCP/IP is, how it works and what it does. Each major protocol is discussed in detail, with sections on configuration, security, IPv6 and Windows 95.