Online Certificate Status Protocol (OCSP) is one of the main protocols used for checking for revoked certificates. This is important in order to ensure that if a server or certificate was compromised, the certificates can be replaced and the old ones revoked to prevent fraudulent use.
These checks can be time consuming, as the browser has to validate the certificate the first time it's used. OCSP stapling is an alternative to OCSP, and alleviates some of the latency issues associated with OCSP. It does this by stapling a cached result directly to the main request. As this result is still signed by the CA, it means that the results are just as secure, yet with no additional latency.
