ICQ supports audio and video chats, as well as instant messaging.They also have apps for tablets and mobile devices and allow for multiple instances so you can always keep in touch with your friends.
If you’re a Googler, and only looking to chat with other Googlers, this is a great chat client.
Like Windows Messenger and Google Talk, Yahoo Messenger requires you to connect with their account.
One of the neatest features of Pidgin is the community plugin development.
The client comes with some official plugins, but you can install third-party plugins that offer flexibility and customization.
It doesn’t offer extra features like video chat or phone calls.