Why do people choose to fake?

Hi every one,

It is so sad to see chess.com too is filled with so much of fake profiles..some create fake profiles, some choose fake or others' photos, yet someother pretent that they are someone else.. choosing symbolic picutres is okay. but there are a number of persons choosing photos of girls.. some even little bit severe. most of those photos were actually seen in matrimonial sites.

what is the psychology behind faking in social sites?

http://en.wikipedia.org/wiki/Factitious_disorder

After reading comments below i have decided to add these lines

(11:43 AM 05-02-2013 Indian standard time)

These accounts are not fake. there is a human touch behind everything. The only thing is they lack confidence or somekind of fear makes them to go in disguise. The behind those we can see the real one. as Masterid says they will always tell the truth afterwards.. - means when they get confidence.  The cynic eys is the curse of this period.

We can reduce this by giving confidence to people or atleast trust them all