• They are connected to the Internet.
• Their Yahoo! Messenger software is running or they are online in Yahoo! Chat or Yahoo! Games.
• They logged in as the Yahoo! ID or profile name in your Friend List.

Important: Your friends will NOT show up unless they have a Yahoo! Account and use Yahoo! Messenger or Yahoo! Chat or Yahoo! Games. Make sure to invite them if they don't have an account.

You can send your friends instant messages whenever they're online. Currently, it's not possible to send instant messages to friends who aren't online.