A divisor is a number that divides another number evenly, meaning there is no remainder. For example, in the equation 12 ÷ 3 = 4, the number 3 is a divisor of 12 because it divides 12 without leaving any leftover. Divisors can be whole numbers, and every number has at least two divisors: 1 and itself. Divisors are important in various areas of mathematics, including factors, multiples, and prime numbers. Understanding divisors helps in simplifying fractions, finding the greatest common divisor (GCD), and solving problems related to number theory.