Whats the points for?

So ive been a member of this site for a few years now and ive always had this question but never asked.
Im probably the only one who doesnt know this but what are the points on here for?
Where do they come from?
And how do you get them?
Its been plaguing me for the longest time i just kept forgeting to ask....

If you know tell me please ^-^ thanks.

By the way if youve never seen this video on you tube you should watch it! xD

http://www.youtube.com/watch?v=l_8yPap-k_s

My friends and i was dyin from lauhter xD

Enjoy.