SNEAK

When a player is sneaking, other players/mobs can not see you entering and
exiting a room. Aggressive mobs also have a chance of not noticing a
sneaking player. Just type SNEAK to attempt to start sneaking. Typing SNEAK
when you are already sneaking will turn it off.

It is easier to backstab something if you sneak up on it. It is rumored
that DEX affects SNEAK

See Also : HIDE