Although there are a lot of instant messengers out there, possibilities are still limited, since it all comes down to just a few big names such as Microsoft (and its MSN Messenger), Yahoo!, Skype and a few others. Yahoo!, for instance, has one of the most popular instant messaging applications out there, with millions of people now using Yahoo! Messenger in every corner of the world.
Basically, Yahoo! Messenger is a software solution that allows users to send and receive messages via an Internet connection, but the application has evolved so much lately that it is now a lot more than that. It comes with built-in photo sharing, file transfer capability, video calling support, online gaming, skins and many others.
You can download it for PCs from http://messenger.yahoo.com and for mobile version visit http://mobile.yahoo.com/messenger
