Can someone explain to me what's the practical purpose of using Facebook ?

[RustBelt]

- No because as a Social Network, facebook has as many purposes (purpos-ii?) as it has Users.

But I can tell you One Practical purpose: It is The Easiest and in many cases, the best way to find Old Friends and Groups of Friends - Ones you have been separated from for Decades. It is however, like other things, "The More Effort You Put INTO It... The More You Will Get Out Of IT."

Explore facebook's Help Topics (Click on "Help", at the bottom of any facebook Page). At first, it probably not make much sense but with repeated visits and familarity, you WILL learn much... maybe not enough to suit you, but you will learn if you want to. (sic)