What characteristics make the sun a star?

The Sun is classified as a star primarily due to its composition and energy generation process. It is composed mainly of hydrogen and helium, undergoing nuclear fusion in its core, which converts hydrogen into helium and releases vast amounts of energy in the form of light and heat. This process creates the immense gravitational forces that maintain its stability and shape. Additionally, the Sun emits its own light, a key characteristic that distinguishes stars from other celestial bodies.