The Stealth skill allows you to avoid detection, both when hiding in place and trying to move about unseen. It pairs well with the Burglary skill.
Overcome: You can use Stealth to get past any situation that primarily depends on you not being seen. Sneaking past sentries and security, hiding from a pursuer, avoiding leaving evidence as you pass through a place, and any other such uses all fall under the purview of Stealth.
Advantage: You’ll mainly use Stealth to create aspects on yourself, setting yourself in an ideal position for an attack or ambush in a conflict. That way, you can be Well-Hidden when the guards pass by and take advantage of that, or Hard to Pin Down if you’re fighting in the dark.
Defend: You can use this to foil Notice attempts to pinpoint you or seek you out, as well as to try to throw off the scent of an Investigate attempt from someone trying to track you.