The creation of the elements in the universe took billions of years and required various processes.

The first few minutes of the big bang produced only hydrogen (H) and helium (He). No new elements were formed until a few hundred million years later when the first generation of stars were born and they started fusing H and He into slightly higher-mass elements, such as carbon and oxygen. Various fusion reactions by multiple generations of stars eventually created elements up to iron (Fe).

However, normal stars cannot produce elements beyond Fe. Creation of elements heavier than Fe required the cataclysmic explosions of supernovas. These violent deaths of massive stars not only completed the natural elements in the periodic table. They also enabled human life, because certain life processes require heavy elements.