Format preserving encryption (FPE) is a cryptographic method that encrypts data while keeping its original format intact. Unlike traditional encryption, which often changes the structure or length of the data, FPE ensures that the encrypted output maintains the same format, such as the same length and character set as the input. This is particularly useful in situations where the data needs to fit into existing systems or databases that expect specific formats, like credit card numbers, social security numbers, or dates. FPE allows sensitive information to be encrypted without disrupting the underlying system that handles or stores the data, providing security while preserving compatibility.