Relationship to Application Caches and History Lists
Applications using HTTP often specify additional forms of caching. For example, Web browsers often have history mechanisms such as "Back" buttons that can be used to redisplay a representation retrieved earlier in a session.
Likewise, some Web browsers implement caching of images and other assets within a page view; they may or may not honor HTTP caching semantics.
The requirements in this specification do not necessarily apply to how applications use data after it is retrieved from a HTTP cache. That is, a history mechanism can display a previous representation even if it has expired, and an application can use cached data in other ways beyond its freshness lifetime.
This does not prohibit the application from taking HTTP caching into account; for example, a history mechanism might tell the user that a view is stale, or it might honor cache directives (e.g., Cache-Control: no-store).