Geostationary Orbit is a path of revolution of Geostationary Satellite. An artificial Satellite is put in this orbit around the Earth at the required height with appropriate horizontal velocity to make it stable in the orbit around the earth. A Geostationary Satellite is a Satellite which is geosynchronous. Its relative velocity with respect to the Earth is zero. So, it appears stationary to an observer on the earth.
The Satellite must complete its revolution in the same period of Earth’s rotation, i.e. 24 hrs. It is stationed at the height of approx 35930 km with orbital radius of about 42000 km. Angular velocity of rotation of the earth and that of the geostationary Satellite are invariably in the same direction.
To be geostationary, a satellite ^needs to revolute at the velocity of about 11060 km/hr. At this velocity it is synchronous with the earth and becomes Geostationary.
Such orbit is called geostationary orbit. Satellite are required to put at the distance of about 3 degree from each other and so only 120 satellites can be accommodated in one orbit.
These orbits have acquired importance because geostationary Satellites are used in communication weather forecast etc. They provide communication with minimum Doppler Effect.
There are many geostationary orbits on the plane of the earth, but especially some orbits are being crowded heavily due to its locational importance. If these orbits get more crowded, it will result into frequency interferences between satellites and they will cause destruction of signals.