Stars evolve from birth to death much as animals or plants do. New stars form in stellar nebulae, made of clouds of plasma, hydrogen and helium. The lifetime of a star varies according to its mass; more massive stars have shorter lifespans than average-sized stars. The dividing line between the two types is around eight times the mass of the Sun; the two types have different life cycles.
Hover over the text of the individual stages to see information about each stage.