The General Number Field Sieve (GNFS) is an advanced algorithm used for factoring large integers, particularly those with hundreds of digits. It is the most efficient known method for factoring numbers of this size and is based on algebraic number theory. GNFS works by finding a suitable number field and using it to create a system of equations that can be solved to find the factors of the target number. The algorithm consists of several stages, including polynomial selection, sieving, and linear algebra. Each stage is crucial for reducing the complexity of the problem. GNFS is particularly effective for numbers that are the product of two large primes, making it relevant in fields like cryptography, where the security of systems often relies on the difficulty of factoring large integers.