A cryptographic hash is a function that takes an input (or message) and produces a fixed-size string of characters, which appears random. This output, known as a hash value or digest, is unique to each unique input. Even a small change in the input will result in a significantly different hash, making it useful for verifying data integrity. Cryptographic hashes are widely used in various applications, including digital signatures, password storage, and blockchain technology. They ensure that data has not been altered and help secure sensitive information by transforming it into a format that is difficult to reverse-engineer.