All stars are basically enormous balls of fire made up of gases which give off heat and light as they burn. Their power comes from nuclear energy.
The life of a star spans billions of years. It is born from clouds of dust and the element hydrogen. A protostar, glowing gas ball, becomes a star when hydrogen atoms combine to form helium. A star can continue to glow for millions of years. When the star finally runs out of hydrogen it starts to cool.
Red supergiants are stars run out of hydrogen. They explode in a violent blast, supernova, but in some cases they may become a black hole.