Final answer:
OCSP, which stands for Online Certificate Status Protocol, provides the revocation status of digital certificates to clients without needing the entire CRL, thus enabling efficient certificate validation.
Step-by-step explanation:
OCSP stands for Online Certificate Status Protocol, and its primary function is to provide the revocation status of a digital certificate. When a client attempts to verify a certificate, instead of downloading the entire Certificate Revocation List (CRL), the client can query the OCSP responder associated with the certificate issuer. The OCSP responder checks the current status of the certificate and returns whether it is valid, revoked, or unknown.