Client asks the cache to validate the response against the server before returning a cached response.
Client asks the server to not store the response in cache.
Client asks the server not to alter the response such as for image compression, optimizations, etc.
Client will only accept a response from cache, otherwise the cache should return 504 (Gateway Timeout)
Server asks client not to use a cached response without validating that the data hasn't changed on the origin server.
Server asks all recipients (including cache servers and browsers) not to store a copy of the response.
Server asks recipients of response not to modify the response such as for image compression, optimizations, etc.
Server tells the client that it may cache the response indefinitely.
Server tells the cache that once a response is expired, it must revalidate data with the origin server.
Server tells the cache that it should only store the response if it understands or is compatible with the requirements for caching.
Server indicates the the response can only be stored in private caches such a local caches in browsers.
Server indicates that a response may be stored in a shared cache such as a CDN.
Same as must-revalidate, but for shared caches such as CDN.