Satellite - is an object, which has been placed into orbit by human endeavor.
Natural satellites:The Moon.
Artificial satellites.Sputnik 1.
The first artificial satellite was Sputnik 1.It was launched by the Soviet Union on the 4th of October 1957.
A few hundred satellites and thousand of unused satellites are orbiting the Earth.
Purposes:Military observationCommunicationNavigationWeather forecastResearches