mIRC is the most popular IRC client available for Windows due to it being so easily modifiable.Unlike XChat before it, HexChat is completely open source software and free of charge on all platforms. It can probably be found in the software repository of your Linux distribution of choice, if not preinstalled. HexChat is the successor to the most popular Linux client for IRC XChat.These will usually limit you to access to a particular channel or network. These are often found on the website of the organization that has an IRC room or channel. There are numerous web clients that can be used to access IRC.Note that these are usually made for Unix-like operating systems such as Linux and OS X. These two in particular are very feature rich and highly extensible - especially the former. Several terminal based IRC clients exist popular ones include WeeChat and irssi.Smuxi is an irssi-inspired, flexible, user-friendly and cross-platform IRC client for advanced users, targeting the GNOME desktop.

Pidgin is a multi-platform instant messaging client which supports IRC, as well as AIM, Yahoo, Facebook and several other protocols.

Wikipedia has a comparison of various IRC clients here. A client is the software that you use in order to interact with the chat environment. Download and install one of the many IRC Clients that are available.

Open mirc chat history