CIII, or C3, is a Roman numeral that represents the number 103. Roman numerals are a numeral system originating from ancient Rome, using combinations of letters from the Latin alphabet. In this system, "C" stands for 100, and "III" represents 3, thus combining to form 103. In various contexts, CIII can refer to different subjects, such as a designation in military units, a specific model of a product, or even a chapter in a book. The meaning of CIII can vary widely depending on the field in which it is used, making it important to consider the context for accurate interpretation.