Stealth is an ability which allows a character to "sneak" around unseen. Mobs can still sense your presence, especially if you move in front of them. Movement speed is reduced but time can be saved by avoiding fights. Stealth level can be improved by the use of certain stealth items (currently pocket items and cloaks).
Burglars gain the ability at level 4. Movement speed is 50% of normal. Burglars can also take a fellow into Stealth if they stay close by use of ; movement speed becomes 30%. Burglars can also suddenly hide from view in combat using (HiPS) which makes them undetectable for 10 seconds.
Warg Stalkers use their own version of , and can also if the battle turns against them.
Wardens can use to move in stealth for a short time, usually to their foes.