Why do stars have different lifespans?

The lifespan of a star depends on its mass. Massive stars burn through their nuclear fuel much faster than smaller ones, leading to shorter lifespans of millions of years. Smaller stars, like red dwarfs, consume their fuel slowly and can live for billions of years. Stars like the Sun fall in between, with lifespans of about 10 billion years. The rate at which stars convert hydrogen into helium determines their energy output and ultimately their longevity.