TCP/IP stands for Transmission Control Protocol/Internet Protocol.
It is a software protocol but it is a network protocol. The one upon which the Internet is based -- Each node must be configured for TCP/IP to function properly.
What is TCP/IP
TCP/IP is basically the binding together of most of the above example Internet Protocols and others such as the X protocol upon which the X window system (popular with UNIX but also device independent window system). TCP/IP also supports routing and name serving essential for internetworking (see below).