Cache-control HTTP header used to specify browser caching policies in both client requests and server responses. Policies include how a resource is cached, where it’s cached and its maximum age before expiring.
The amount of time it takes for a cached copy of a resource to expire (in seconds).
Browser may cache a response, but must first submit a validation request to an origin server.
Browser aren’t allowed to cache a response.
Resource can be cached by any cache.
User specific resource, browser can be cached, but only on a client device.
Additional HTTP Cache Headers
Sat, 13 May 2017 07:00:00 GMT, same purpose as max-age directive
The identifier version of the resource used to detect the changed resource.
A header that determines the responses that must match a cached resource for it to be considered valid. For example, the header Vary: Accept-Language, User-Agent specifies that a cached version must exist for each combination of user agent and language.