Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?

The stars are very far away from the Earth and it is not convenient to express such distances in kilo¬metres. Thus, such large distances are expressed in unit known as light year. If we say that a star is eight light years away from Earth, it means that the light from star will reach the Earth in eight years.