How do chess games become draws?

I only understand when both sides are reduced to kings. However sometimes when I am kicking the computers ass ALOT the game becomes a draw and is counted as a loss in my statistics. Why is this?

A draw is not a loss.  

You might have a draw declared because the eacxt same position is repeated three times (every piece is in the exact same place 3 times) and the draw is claimed by your opponent

or because absolutely nothing is happening in the game and the draw is claimed by your opponent after 50 moves without either side making a capture or pawn move 

but it doesn't count as a loss in anyone's statistics.

In Window's 7 "Chess Titans" a draw will count as a loss in your statistics.