An Oblivious Pseudorandom Function (OPRF) is a cryptographic protocol that allows two parties to jointly compute the output of a pseudorandom function (PRF) without either party revealing their private input to the other. Typically, one party holds the input value, and the other holds the secret key for the PRF. Through the OPRF process, the input holder receives the function output as if the key holder had computed it, but neither party learns the other's secret. OPRFs are widely used in privacy-preserving authentication, password-based key exchange, and secure multi-party computation, enhancing security by minimizing data exposure during sensitive operations.