Why don’t satellites fall into the Earth?

Satellites can continue to orbit around the Earth without falling, because two powers – “gravity” and “centrifugal force” are keeping the balance. Gravity is the power that the Earth pulls satellites. Centrifugal force is the power that satellites tend to move away from the Earth by orbiting around it. Satellites are released from the rockets at the proper speed in a balance of gravity and centrifugal force, so they can keep orbiting around the Earth.
However, strictly speaking satellites may be affected by frictional force caused by the Earth’s atmosphere depending on the difference of environment such as the altitude of satellites. As the frictional force increases, the altitude of the satellite will decrease little by little and fall into the Earth. Satellites are constantly monitored from the Earth so that they can maintain the determined orbit.