What are stars made of?

Stars are made of very hot gas. This gas is mostly hydrogen and helium, which are the two lightest elements. Stars shine by burning hydrogen into helium in their cores, and later in their lives create heavier elements. Most stars have small amounts of heavier elements like carbon, nitrogen, oxygen and iron, which were created by stars that existed before them. After a star runs out of fuel, it ejects much of its material back into space. New stars are formed from this material. So the material in stars is recycled.