This article is about the celestial phenomenon. For a list of stars, see Category: Stars.

Stars are massive, luminous spheres of plasma held together by gravity. By the end of their lives they may also contain degenerate matter. By the very end of their lives, their internal pressure is often too weak to resist their own gravitational pull, and they collapse into black holes.

Stars are often orbited by planets and are then referred to as suns. A star's distance from a planet is one of many factors determining whether and what sort of life can evolve there.