Sweet Baby

Besides using freshness information and validation, there are a number of other things you can do to make your site more cache-friendly.

Use URLs consistently — this is the golden rule of caching. If you serve the same content on different pages, to different users, or from different sites, it should use the same URL. This is the easiest and most effective way to make your site cache-friendly. For example, if you use “/index.html” in your HTML as a reference once, always use it that way.

Use a common library of images and other elements and refer back to them from different places.

Make caches store images and pages that don’t change often by using a Cache-Control: max-age header with a large value.

Make caches recognise regularly updated pages by specifying an appropriate max-age or expiration time.

If a resource (especially a downloadable file) changes, change its name. That way, you can make it expire far in the future, and still guarantee that the correct version is served; the page that links to it is the only one that will need a short expiry time.

Don’t change files unnecessarily. If you do, everything will have a falsely young Last-Modified date. For instance, when updating your site, don’t copy over the entire site; just move the files that you’ve changed.

Use cookies only where necessary — cookies are difficult to cache, and aren’t needed in most situations. If you must use a cookie, limit its use to dynamic pages.

Minimize use of SSL — because encrypted pages are not stored by shared caches, use them only when you have to, and use images on SSL pages sparingly.

Check your pages with REDbot — it can help you apply many of the concepts in this tutorial.