Pidgin chat client

Pidgin is an open source client program for instant messaging, also called IM or Internet chat. It is included in most Linux or BSD distributions and is available for other systems including Microsoft Windows and the Apple Macintosh. It handles multiple protocols including Microsoft's MSN, AOL's AIM protocol, Internet relay chat, the QQ chat system which dominates the market in China, and Google talk.

A common add-on is another open source application, off-the-record messaging, which provides encrypted connections over any protocol Pidgin supports.

The Pidgin web site has much more information.