Geostationary satellite: A geostationary satellite is an earth-orbiting satellite, placed at an altitude of approximately 35,800 kilometers (22,300 miles) directly over the equator, that revolves in the same direction the earth rotates .At this altitude, one orbit takes 24 hours, the same length of time as the earth requires to rotate once on its axis. The term geostationary comes from the fact that such a satellite appears nearly stationary in the sky as seen by a ground-based observer.
Advantages of Geostationary Satellites: 1. This satellite remains almost stationary in respect to a given earth station. Consequently expensive tracking equipment is not required at earth stations. 2. High altitude geosynchronous satellites can cover a much larger area of the earth than their LEO satellite counterpart. 3. There is no need to switch from one satellite to another as they orbit overhead. Consequently there are no breaks in transmission because of switching times. 4. The effects of Doppler shift are negligible