Yahoo! Messenger is a popular advertisement-supported instant messaging client and associated protocol provided by Yahoo!, that allows you to see when friends come online and to send them instant messages.It also can alert you to new e-mail in your Yahoo Mail or Yahoo Personals accounts, or when you have upcoming events recorded in your Yahoo Calendar. Yahoo Messenger offers firewall support, a standby mode that minimizes the program until an Internet connection is made, the ability to save and print your conversations, and a tabbed interface that provides quick access to your favorite stocks, news, and sports scores.Yahoo! Messenger is provided free of charge and can be downloaded and used with a generic Yahoo! ID which also allows access to other Yahoo! services, such as Yahoo! Mail, where users can be automatically notified when they receive new email.Yahoo! also offers PC-PC, PC-Phone and Phone-to-PC service, file transfers, webcam hosting, text messaging service, and chat rooms in various

New In Yahoo! Messenger 11:
Invite your friend to play a game - In addition to instant messages, text messages, voice and video calls, you can now play popular social games such as Mafia Wars and Fishville right within Yahoo! Messenger.
- Keep up with friends wherever they are - View, comment on and like updates from Yahoo! Pulse, Flickr, Facebook, Twitter, and more, all from right within Yahoo! Messenger.
- Post one status to multiple social networks - Share your Messenger status simultaneously on Yahoo! Pulse, Facebook, and Twitter.
- Chat with Facebook friends - In addition to your friends on Windows Live, you can now IM your Facebook friends. Continue your conversations on the go using Mobile Web Messenger, SMS Messenger or Yahoo! Messenger App for Android.
- Always be available - Stay signed in to multiple PCs simultaneously so you never have to miss a message.
- Easy access to recent conversations - Retrieve all your IM conversations from any PC where you have signed in to Yahoo! Messenger.
- Personalize your experience with fresh new skins - Express yourself and show off your personality with one of the 7 newly added messenger skins