There are four types of stylus pens. 1. Capacitative passive stylus - the most basic stylus without any useful functionality for the artists; 2. Dedicated active stylus - these are styluses specifically for iPads, and Surface and Samsung drawing tablets with pressure sensitivity, tilt recognition, and palm rejection; 3. Bluetooth active stylus - same as dedicated styluses above, they have all the necessary features and aim to be cross-compatible, which doesn't always work out; and 4. USI active stylus - a new tech initiative aiming to create ultimate cross-compatible styles which currently work only for Chromebooks.