Shadow people are dark, human shapes typically seen moving at night and the most common form of ghosts that people witness. Shadow people often flee in the presence of people in physical bodies, especially if they realize they have been detected, and are often viewed out of the corner of one's eye
Dez said it best, also know not all shadow people cause harm, they are usually timid and afraid, however, they may check you out in a curious way, I see shadows and rarely have a hostile one. Most check check me out then go about their way.
Depending on the strength of the shadow person, they can be quite malevolent and bothersome, but the ones that aren't as strong are merely a nuisance, similar to a deceased person's spirit moving your keys every day.