Integer factorization is the process of breaking down a composite number into its prime factors. A composite number is a positive integer that has at least one positive divisor other than one and itself. For example, the number 15 can be factored into the prime numbers 3 and 5, since 3 × 5 = 15. This concept is important in various fields, especially in cryptography, where the security of many encryption systems relies on the difficulty of factorizing large integers. The RSA algorithm, a widely used encryption method, depends on the fact that while it is easy to multiply two large prime numbers, it is much harder to reverse the process and find those primes from the product.