The most common elements are the elements found in the highest abundance in the universe. These elements are hydrogen, helium, oxygen, carbon, nitrogen, and neon. Hydrogen is the most abundant element, making up about 75% of the universe's elemental mass. Helium is the second most abundant element, making up about 24%. Oxygen, carbon, nitrogen, and neon make up the remaining 1%. These elements are essential for life on Earth and are found in all living things.