HTTP caching involves setting cache control headers in your responses. There are many of these headers, which have been added over the years from different standards and various versions of the protocol. You should know how these are used, but you should also understand how the uniqueness of a cacheable resource is determined, for example, by varying the URL or by altering only a part of it, such as query string parameters.
Many of these headers can be categorized by the function and the version of HTTP that they were introduced with. Some headers have multiple functions and some are non-standard, yet are almost universally used. We won't cover all of these headers, but we will pick out some of the most important ones.
There ...
