IRC

IRC is a primitive chat program that was one of the first ever uses of the internet, alongside newsgroups and MUDs, and predate both e-mail and the world wide web.

IRC and talkers were the forerunner to instant messenger programmers like ICQ.

Using IRC, you connect to a #channel then to emote something you type /me smiles. The / character is used for various commands. Otherwise, you simply talk, although you can go to private chat with various people.

IRC was very simple and today is basically the same as it was from the beginning, except that now you can use it via a java world wide web connection, connecting to it is easier, and you can now connect to multiple channels at once.