C12, also known as Carbon-12, is a stable isotope of carbon that has six protons and six neutrons in its nucleus. It is the most abundant carbon isotope, making up about 98.9% of all carbon found in nature. C12 is essential for life, as it is a key component of organic molecules, including carbohydrates, proteins, and fats. In addition to its biological significance, C12 is used as a standard for measuring atomic weights in chemistry. The atomic mass unit (amu) is defined based on the mass of C12, which helps scientists accurately compare the masses of different elements and compounds in various scientific fields, including biochemistry and materials science.