IRC (Internet Relay Chat) is a terminal type based messaging system
it's been around since the days of text only internet
the extensive use of the even older ACSII art was used to great effect
on IRC and of course the emoticons and the "New" SMS shortcut spelling
started here as well, well before the days of SMS

if you want to have a play download the program called mIRC
still plenty of networks and servers with millions still using it
chatting and transfering files etc

I still use it often

Kev