You are skilled at avoiding detection, allowing you to slip past foes or strike from an unseen position. This skill covers hiding and moving silently.
Your Stealth check is opposed by the Perception check of anyone who might notice you. You can move up to half your normal speed and use Stealth at no penalty. When moving at a speed greater than half but less than your normal speed, you take a –5 penalty. It's impossible to use Stealth while attacking, running, or charging.
A creature larger or smaller than Medium takes a size bonus or penalty on Stealth checks depending on its size category:
Fine +16, Diminutive +12, Tiny +8, Small +4, Large –4, Huge –8, Gargantuan –12, Colossal –16.
If people are observing you using any of their senses (but typically sight), you can't use Stealth. Against most creatures, finding cover or concealment allows you to use Stealth. If your observers are momentarily distracted (such as by a Bluff check), you can attempt to use Stealth. While the others turn their attention from you, you can attempt a Stealth check if you can get to an unobserved place of some kind. This check, however, is made at a –10 penalty because you have to move fast.
If you've already successfully used Stealth at least 10 feet from your target, you can make one ranged attack and then immediately use Stealth again. You take a –20 penalty on your Stealth check to maintain your obscured location.
Usually none. Normally, you make a Stealth check as part of movement, so it doesn't take a separate action. However, using Stealth immediately after a ranged attack (see Sniping, above) is a move action.