Mac OS X's iChat software offers an easy way to exchange real-time text messages (instant messaging), chat using audio or video, transfer files, and share photo albums, movies, presentations, and other multimedia data across the Internet. It works with MobileMe accounts as well as with AIM (AOL Instant Messenger), Google Talk, and Jabber accounts — and with other Macs on your local network via Bonjour.
iChat includes two categories of security settings. First, you can specify, for some account types, which users can or can't contact you and whether anyone can see that you're idle. And second, MobileMe users can encrypt iChat sessions in their entirety to avoid the possibility of chats being intercepted in transit.
To change iChat's privacy settings, follow these steps:
With iChat running, log in to each of your accounts if you haven't already done so.
Choose iChat Preferences to open the Preferences window and then click Accounts to open the Accounts pane.
In the Accounts list on the left, select any MobileMe, Mac.com/.Mac, or AIM account. Privacy settings don't apply to other account types.