We use satellites for different purposes and all satellites can be placed in one of the following categories: Communications Satellites
Distribution of television and audio signals, and telephone connections via satellite are done by Communications Satellites. These types of communications typically need a satellite in geostationary orbit. Today geostationary satellites are used to provide voice, audio and video communications like DTH TV. Navigation Satellites
These satellites are of enormous help to transportation companies, especially transportation over water and through the air. The US GPS satellites are in Low Earth Orbit (LEO) and can determine position with a precision of 1 cm (0.4 inch). However, that very precise positioning is available for military purposes only. Weather Satellites
Observing the earth is the task for weather satellites, and then especially what happens in the atmosphere. Different kinds of cameras, like infrared and normal cameras are used to observe either the same part of the earth, from a geostationary orbit, or more closely from polar orbits to get more detailed pictures. These low orbit weather satellites focus more on the study of the atmosphere than on the current weather itself. Military Satellites
Very similar to weather satellites, military satellites are also used for observing the earth. They generally have higher resolution cameras and they use encryption as well. Sometimes these types of satellites have very eccentric orbits to pick up sensitive information from friendly as well as hostile countries. Scientific Satellites
Observing the earth for scientific purposes is also very good possible with satellites. Making maps with low polar...