iChat Version 1
The sample Pics above are in fact from iChat 3 which added the Jabber option seen. The last Pic is obivously a sample of the Video shown at the time and this was added at iChat 2.
iChat 2 was actually a Beta Trial available for Jaguar just prior Panther (10.3.x) being released and both Jaguar and Panther had versions that were called iChat 2 AV but they were not transferable from one OS to the other.
What Can It Do.
iChat (version 1) can IM other AIM based/compatiable IM clients. This means you can Text chats to Buddies who have valid AIM screen names that include @mac.com Email IDs whether they are Full and Paid for or Trial accounts (that work after the 60 Days ) or lasped (full account no longer paid for) ones.
It can send and receive Files and send Pictures as part of the Text chat. It can join Group Chats (or "Rooms").
Chatrooms follow two basic Formats. Predetermined almost Permantent Rooms dedicated to something like a Celebrity or interest and ones created on a more Ad-hoc basis for a group of friend or Buddies. This determines how the Room or Group chat is named.
Sending a file whilst Text Chatting or Sending a Pic in the Chat changes the Chat from an everyday Text Chat into a Direct Chat. This changes the Protocol that IChat uses over the Internet from TCP to UDP. This can be important to some Routers and Modems not only in iChat (ver 1) but the later versions as well
iChat made it's it way into the Apple Applictaion fold in about 2003 with the first version. We are talking at the time of Jaguar (10.2.x)
At that point it was just a basic AIM client. That means that Apple developed an app that worked with other Clients that use the AIM Service. They came to an agreement with AIM that @mac.com email IDs would be recognised by the AIM Servers as valid AIM screen names.
As with other versions of iChat the Password fro any Screen Name has to be 16 Characters or less to be accepted by the AIM Servers fo Login. As @Mac passwords can be longer this needs to be watched.
About iChat
iChat is an Instant Message and Video and Audio only chat application.
It uses the AIM Service as the Text message part but from version 3 onwards can also join Jabber servers including GoogleTalk.
It can send Files and Pics to other iChat Users and in certian circumstances the Pics are displayed in the Chat window.
In later versions it can have add-ons that enhance video features that have then been somewhat included by Apple in Version 4
