The chemical element that has the atomic number 6 is carbon. Carbon is fundamental to all known life forms, serving as the building block for organic molecules such as proteins, lipids, nucleic acids, and carbohydrates. Its unique ability to form four covalent bonds with other atoms allows for the creation of complex structures, including chains and rings. Carbon exists in various allotropes, including graphite, diamond, and graphene, each with distinct properties. Importantly, carbon is also a significant component of fossil fuels and is involved in the global carbon cycle, which is crucial for regulating Earth's climate.