mIRC

mIRC is a full featured Internet Relay Chat client for Windows that can be used to communicate, share, play or work with others on IRC networks around the world, either in multi-user group conferences or in one-to-one private discussions.

It has a clean, practical interface that is highly configurable and supports features such as buddy lists, file transfers, multi-server connections, SSL encryption, proxy support, UTF-8 display, customizable sounds, spoken messages, tray notifications, message logging, and more.

mIRC also has a powerful scripting language that can be used both to automate mIRC and to create applications that perform a wide range of functions from network communications to playing games.