Google talk includes chat services, icons,etc like their competitors (Yahoo Messenger, MSN Messenger, AOL) and it also includes VoIP, with an incredible voice quality.
If you want to talk with your friends, both you must have Google talk installed, and once you have installed it, you can start talking as long as you want...for FREE!
Google Talk is compatible with Apple iChat, Gaim, Adium, Trillian Pro and Psi.
Google Talk enables us to quickly and easily talk or send instant messages to our friends for free. Calls are made through our computer using the latest voice technology; all we need is an Internet connection, a microphone and a speaker!