1. Proper Motion: This refers to the apparent movement of a star across the sky as seen from Earth. It's caused by the star's actual motion through space, perpendicular to our line of sight. Even though stars seem fixed, they all have proper motion, but it's often too slow to be noticed over a human lifetime.

2. Radial Velocity: This refers to the movement of a star directly towards or away from Earth. We can detect this by observing the Doppler shift of the star's light. When a star is moving towards us, its light is shifted to shorter wavelengths (blue-shifted), and when it's moving away, its light is shifted to longer wavelengths (red-shifted).

3. Orbital Motion: Many stars are part of binary or multiple star systems, where they orbit around a common center of gravity. This orbital motion can be quite complex, with stars moving in elliptical or even chaotic paths.

It's important to note that these types of motion are often combined. For example, a star might have both proper motion and radial velocity, meaning it's moving both across the sky and towards or away from us.