Final answer:
Stars are made predominantly of hydrogen, which undergoes nuclear fusion to form helium, releasing energy in the process.
Step-by-step explanation:
The main element that stars are made of is hydrogen. Hydrogen is the most abundant element in the universe and serves as the fuel for nuclear fusion, which powers the stars. In the core of a star, hydrogen atoms combine to form helium through the process of fusion, releasing a tremendous amount of energy in the form of light and heat.
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