Facebook Addiction

Why are some people so addicted to facebook?

They will log in and check on the postings / notifications almost every min.

Just take a train or go to any cafes you will see many people checking their Iphones etc to surf on facebook. Some will even share with the whole world where they are now.

Is it really necessary? I mean you will need to tell the whole world what you are doing / where are you now?

Let's see how long this paradigm will last...