You can chat one-on-one or conduct a multi-person conference.  iChat requires access to the Internet and a compatible account from services such as MobileMe (previously .Mac), AIM (AOL Instant Messenger), Google Talk, or Jabber.

Supported Instant Messaging Accounts and Protocols

• AIM (AOL Instant Messenger)
• Jabber (as of Mac OS X 10.4 Tiger)
• Bonjour (previously called Rendezvous)

New iChat features in Mac OS X Leopard
Apple added several new features in iChat for Mac OS X Leopard.  Some of the key new features include:

• Backdrops - allows you to add a backdrop behind you.
• iChat Theater - allows you to show files on your Mac during your video chat.  You can show photos, presentations, and movies.
• Screen Sharing - it's collaborate made easy.  You can browse the web together and work on documents at the same time.
• Photo Booth effects - you can use many of the same effects found in Photo Booth directly in iChat.  Have fun as you alter how you look!

Other noteworthy features are: new alerts, recording, multiple logins, animated icons, tabbed chats, and File Transfer Manager.

Video Chatting Requirements
An iSight video camera or Mac compatible web cam is required for video chatting.  Note that most new Mac models include an integrated iSight video camera.