![The Sun is a star powered by nuclear fusion in it's core.](http://static.sciencelearn.org.nz/images/images/000/003/250/full/Average_Star.jpg?1674170379)
An average or medium star is less than 3 times the mass of the Sun. Stars are powered by nuclear fusion in their cores, mostly converting hydrogen into helium and liberating tremendous amounts of energy.
Acknowledgement: JPL-Caltech National Aeronautics and Space Administration (NASA)