Google Talk is a simple and free way to talk with and send instant messages to your friends. Like Gmail, Google Talk uses Google's innovative technologies to help people communicate more impactfully and efficiently. Think of it as Google's approach to communications.
Google Talk is easy and intuitive to use. All you need to make free calls is an Internet connection, a microphone, and a speaker. After you download Google Talk, sign in with your Gmail username and password. Invite your friends to download Google Talk, and once they do, you'll be able to talk or IM with them instantly.

The license of this software is Freeware, you can free download and free use this instant messenger software.