Castling

When is it better to castle queen side and when is it better to castle King side?
Why is it not called rooking?
It's not called rooking because when you 'rook' someone it usually refers to mating them on the back rank with a rook when they have forgotten to create an escape square for their king.
When is it better to castle queen side and when is it better to castle King side?
Why is it not called rooking?