There are three mechanisms to control a cache defined in HTTP standard, which are as follows:
Expiresresponse header will give a date when the document becomes stale, and
Cache-Control(the max-age directive) will inform the cache how many seconds the response is fresh (valid) for.
Last-Modifiedheader is in response, a cache can make a next request using the
If-Modified-Sinceheader and check if it has changed. The