Backstabbing is a thief skill that allows you to place your dagger in your opponent's back at the precise point at which it will cause the most harm. A successful backstab gives a damage multiplier, depending on level. Note that you must be sneaking successfully or be hidden from your opponent and you must be wielding an appropriate piercing weapon.
The act of stabbing someone in the back will be carried out in the aggressive mood, but afterwards you will return to your previous fighting mood.
The chance of successfully backstabbing a person depends on how well you have practiced backstab and sneak at your guild. Note also that it is easier to backstab a victim in certain types of terrain (eg. forests) than others, and harder to backstab someone who has high perception. You can backstab sleeping or blind persons with a higher chance of success, even if you are not hiding or sneaking.
If you try and backstab someone who can see you, you will get a nasty surprise.
> backstab ruffian