This documentation is work in progress ;)
Yaaic is a mobile Internet Relay Chat (IRC) client for Android devices.
Internet Relay Chat (IRC) is a form of real-time Internet text messaging (chat) or synchronous conferencing. It is mainly designed for group communication in discussion forums, called channels, but also allows one-to-one communication via private message as well as chat and data transfers via Direct Client-to-Client. (Wikipedia)
For some more information about IRC see http://www.irchelp.org/.