Internet Relay Chat
Users of IRC need an IRC client. An IRC client is a computer program that works with IRC.  There are many clients. Some of these clients run in the web browser. Other clients run as an application.  Popular stand-alone clients include mIRC for Microsoft Windows, and XChat for Linux and Microsoft Windows. The Opera web browser has an IRC client built into the browser. ChatZilla is a chat client which is a plugin to Mozilla Firefox.