The chemical element found in abundance in stars is hydrogen. About 74% of the universe's elemental mass is hydrogen, and it plays a crucial role in the processes that power stars through nuclear fusion. In stars, hydrogen atoms fuse to form helium, releasing vast amounts of energy in the process, which produces the light and heat we observe. The abundance of hydrogen in stars is essential for the creation of heavier elements, making it a foundational element in the structure of the universe and the life cycles of stars.