P-1, or the P-1 algorithm, is a mathematical method used in number theory, particularly for factoring large integers. It is designed to find prime factors of a composite number by using a probabilistic approach, which means it can efficiently identify factors without needing to test every possible divisor. The algorithm works by selecting random numbers and performing modular arithmetic to find potential factors. It is especially effective for numbers with small prime factors. P-1 is often used in cryptography and computer security, where factoring large numbers is crucial for breaking encryption codes.