Once on the New Messages screen, users will see an explanation of how the system works, highlighting the various features such as the ability to view all message threads regardless of the communication channel they originated from; see the full history of particular conversations and see a folder of messages from their Facebook friends.

Screenshot credit: Facebook

Users can link their existing email account - such as Gmail or Hotmail - to the system or create their own Facebook email address with the format of username@facebook.com.

The system prioritises messages from a user's Facebook friends over other messages – such as bills – which are filtered into a separate folder called Other. If someone who is a friend but not on Facebook sends an email, the user can easily move future emails from that person to the main Messages inbox.

Users can also add and remove people – including themselves - from threads, add attachments from outside Facebook and forward messages.

Account Settings allows users to choose to bounce any emails that aren't from friends, preventing any unwanted contact.

Screenshot credit: Facebook

On the same screen users can also choose to add SMSes to their Facebook Messages by inputting their location, mobile network and phone number.

According to Facebook engineer Joel Seligstein the revamped Messages system will spare users having to choose which communication method people prefer to be contacted by, instead allowing them to type the person's name and have the message routed through the preferred communication channel automatically.

"All this means that for many Facebook users they will never need to ever move outside the Facebook portal. That will obviously attract more and more advertising dollars to Facebook," Richard Holway, chairman of analyst house TechMarketView, wrote in a research note.

Screenshot credit: Facebook

Once the user has hooked up the various communication methods to Messages, they will see a single stream of conversations regardless of what medium they originated in.

Different images appear next to the message threads depending on where they've come from: a Facebook profile picture will denote direct messages sent within Facebook while email messages will be shown by an envelope, SMS conversations by a phone symbol and chat exchanges by a Facebook Chat icon.

The upgrade to Messages will be rolled out to all users over the next few months, starting in the US. Users will receive an invite after which they will be able to invite friends to use the new system too.

Screenshot credit: Facebook