There are several types of satellites:
Communications satellites act as relay stations in space.People use them to bounce messages from one part of the world to another. These messages can be telephone calls, TV pictures, or even Internet connections like the one you're using now.There are more than 100 communications satellites orbiting Earth.Communications satellites are in geosynchronous orbit (from geo = Earth + synchronous = moving at the same rate). That means that the satellite always stays over one spot on Earth. The area on Earth that it can "see" is called the satellite's "footprint.
Weather satellites are used in measuring temperature, moisture and solar radiation in the atmosphere. Also they are used in search and rescue operations.
Many satellites in orbit conduct scientific experiments and observations.
Remote-sensing satellites, study Earth's surface. From 300 miles (480 km) up, this satellite uses powerful cameras to scan the planet. The satellite then sends back valuable data about global environments.