What is timeline on fb?

[batman]

is it optional to download an what is it exactly or is like mandatory?

[MusicFan754]

never heard of that

[Zac]

It's mandatory, but it's just a new look for your profile page, not your news feed, photo albums, etc. You can get it now, but it will become mandatory on Dec 22 (a week from today). It's really pretty cool

[Rom Cartridge]

A Timeline is the new virtual space in which all the content of every Facebook user will be organized and shown.

Although for the moment Facebook did not make a clear statement about the deployment of the upgrade in any of its official pages, and as a consequence there is a lot of false information going around, experienced users know that Facebook upgrades of this size are never optional.

Besides, there are clear evidences that indicate that there will be no way to go back to the old Profile. Take a look at the article in the source to see what those evidences are.