IM with friends on other networks
You can use Yahoo Messenger to share instant messages with friends who are on other instant messaging networks, like Windows Live™ Messenger (previously MSN). All your friends can be on your contact list so you can easily see when they're online, and IM them whenever you want. Gone are the days of having to use multiple IM programs to connect with all your friends. Just keep them all in one place on your Yahoo Messenger list.
To add a friend from another network, simply click the "Add Contact" button in Yahoo Messenger, enter your friend's email address, and select the network they're using.
Then, they'll show up on your Yahoo Messenger contact list. You can see when they're online and send them instant messages. Plus if you send an IM while they're offline, they'll get the message once they log back on.
Yahoo Messenger allows you to instant message with friends on these networks: