This is skill to move without detection. You know how to conceal yourself in a given area, prowl silently to escape detection, and are generally not seen or heard. Your movement speed is reduced when you stealth. You may have to cause a distraction to remove attention from your direction of travel.
You also make an excellent shadow. You know how to safely follow others, either by foot or vehicle. You always stay on the high ground to observe a stationary target. You can lose an unwanted shadow with this skill.