Why is the distance between stars and planets expressed in light years?

The distance between the Earth and stars and the distance between the stars is very large. The stars are millions of times farther away than the Sun. the Sun is nearly 150,000,000 Km i.e. 150 million Km away from the Earth. It is inconvenient to express these distances in kilometres. Therefore, these large distances are expressed in light years. For example, the distance of the Sun from the Earth may be said to be about 8 light minutes.