Are used for data communication, for transmiting TV signals or for weather information.
Satellites move in this orbit from west to east, and are always posicionated over the same point on the Earth.
Medium Earth Orbit (MEO satellites), used for data and TV transmissions.
Low Earth Orbit (LEO satellite), used for geological data transmission on tectonic plates and for telephone communications.
Highly Elliptic Orbit (HEO satellite), used to map details of the Earth surface that aren´t detectable by others satellites.