Yes, if someone you’re emailing also uses Yahoo! Mail or Yahoo! Messenger and they’re online, you can type a conversation with them instead of sending an email and waiting for their response. Your written message instantly appears in a separate tab in their Mail window (or a new Conversation window for Messenger users), and their response shows up whenever they press “Enter” or click Send.

Of course, you can also send them a regular email. Chat just gives you another, instant way of communicating with any other Yahoo! Mail or Messenger user if they’re online at the same time as you.

You don’t have to download anything to use it. Chat’s just a new, free part of the new Yahoo! Mail.