TCP/IP is the network protocol, along with the routing protocol BGP that make up the Internet. Because of the rise in popularity of the Internet, TCP/IP is the most popular networking protocol of all time. There simply is an amazing amount of OS's and platforms that support TCP/IP.
The most popular implementation of TCP/IP came from the 4.3 BSD release, because of the BSD copyright, people were free to adapt the software to their own needs.
Vint Cerf is largely credited with creating the protocol.
TCP/IP is a family of several protocols.
Lower OSI protocols
Address resolution protocol.
Serial line protocol. SLIP was a popular way to connection machines with TCP/IP over leased lines and modems, anything that could talk in a serial manner (like the most popular RS232 ports). The big drawback to SLIP was that each end had to be pre-configured. This made things like dialup banks exceptionally difficult to maintain, as each user would be assigned a static address. However it did work out fine for 'infrastructure' as they tended not to move.
SLIP has been largely supplanted by the PPP protocol.
Point to point protocol.
Higher OSI protocols
Transmission control protocol
User datagram protocol
Historical Systems Including TCP/IP
This list is far, far from exhaustive, and primarily meant for systems from the 1980s, before TCP/IP became universal on all but embedded systems.
- BSD Unix from 4.2 onward.