What to study first to create a Chatroom?

Question

What are some languages I should study to create a Chatroom?

Answer 1

The programming language doesn't matter; you can create a chatroom in any programming language. What you probably want to know about is the Extensible Messaging and Presence Protocol (XMPP), how t perform network communication in the language of your choice, and any libraries that might help such as libpurple if you want to integrate with any of the standard IM protocols.

Answer 2

IRC (Internet Relay Chat) is probably what you need.