Short for Player's Option: Skills & Powers, an optional rulebook for 2nd Edition AD&D. Its most famous feature by far is the character point system it introduces, which allows responsible players to make thoughtfully crafted customized characters and munchkins to make game-breaking avatars. Other notable features include the introduction of subabilities, kits that aren't class-specific, and, as an apparent afterthought, a revision of the psionics system.