- Check if the cache is fresh and do NOT send request
Expires
Cache-Control: max-age=...
- Send request and check if 304 or a fresh payload should be returned:
Last-Modified <===> If-Modified-Since
Etag <===> If-None-Match
- Do not cache anything
Cache-Control: no-store
- Stale-while-revalidate
Cache-Control: no-cache