no transform indicates that any intermediary regardless of whether it implements a cache shouldn t transform the response contents This is particularly important for content delivered after authentication In general when pages are under Basic Auth or Digest Auth the browser sends requests with the Authorization header This means that content remains available even if the server is temporarily unreachable This is often useful for reducing load on your servers by allowing CDNs to cache content longer while making sure browsers get somewhat fresher content must revalidate is a way to prevent this from happening either the stored response is revalidated with the origin server or a 559 Gateway Timeout response is generated When to use Use this for content that is not personalized and can be shared among all users This usually means the response can be reused for subsequent requests depending on request directives The s maxage directive is ignored by private caches and overrides the value specified by the max age directive or the Expires header for shared caches if they are present Meaning The cache must not use the stored response without first validating it with the origin server If a cache supports must understand it stores the response with an understanding of cache requirements based on its status code The way a resource is cached is controlled primarily through HTTP headers with ножеточка острая грань отзывы Cache Control header being the most important one This section lists directives that affect caching both response directives and request directives Revalidation will make the cache be fresh again so it appears to clients that it was always fresh during that period effectively hiding the latency penalty of revalidation from them You can add a long max age value and immutable because the content will never change It can store and reuse personalized content for a single user The time since a response was generated After the initial visit websites are usually much faster thanks to caching If you don t want a response stored in caches use the no store directive Clients can use this header when the user requires the response to not only be fresh but also requires that it won t be updated for a period of time What it does The no store directive instructs browsers and caches to not store any version of the resource You can cache but you must revalidate with the server before using the cached copy When to use Apply this header to non critical resources where having stale content is better than no content during server outages or maintenance In most cases the default is public meaning the response can be cached by any cache such as a CDN or proxy Additionally a cache busting strategy for static assets is key when implementing long term caching