What are the two kinds of telemetry and what are their purposes? Commanding: what is the basic purpose of commanding a satellite?

Explain the purposes of satellite Tracking, Telemetry and Commanding. Tracking: how is satellite position and velocity determined, and how is this information communicated to satellite operators and users? Telemetry: what are the two kinds of telemetry and what are their purposes? Commanding: what is the basic purpose of commanding a satellite?