Mark Zuckerberg on Facebook's revamped messaging system
Facebook has revamped its messaging system to make it the main way people communicate with friends and family.
Confounding rumours about what Facebook would announce, founder Mark Zuckerberg said the system was "not e-mail".
Instead, he said, it was modelled on instant messaging systems and will route messages to people no matter how they are using Facebook.
Mr Zuckerberg said people expected communication to fit expectations set by their use of Instant Messaging, SMS and Facebook's own chat system.