What  is Caching?

Where a context is computing, cache is a place for storing data temporary. This means compute once, use many times.

There are two scope of caching:

  1. Server side
  2. Browser (client side)

Server Side Cache

When some one visits a page of your WordPress website, all corresponding PHP scripts of your theme and WordPress core should be executed by server and produce HTML file. Of course it takes time and resources from host server. But imagine this, the HTML page is cached on server and every other visitors of this page, fast reach to this cached file.

Server side caching has privileges:

  • Reduce server response time  (Google recommend: under 0.2 second)
  • Reduce computing load on host server

Browser Cache

Browser can temporary store web page resources on your computer. HTML files, CSS style sheets, JavaScript scripts, images and all type of media files can be locally stored by browser. Next time your browser wants those files, no need for looking up in the internet and wasting your time, they are in local storage and their loading would be much faster.

There are many different mechanisms for browser caching but we don’t want to make it very technical and talk about them briefly in cache plugins tutorials.

Browser caching has privileges:

  • Do not send request for one file in every page view, so increase the page loading speed
  • Download a file once, so save Internet traffic and bandwidth

Cache Plugins

Sophisticated WordPress cache plugins do the set up of both caching mechanisms (server side & browser cache) for you.

They can store one HTML version of your pages on your server. So response to every page request will be as fast as possible. Of course this stored pages refresh once in a while or after posting new content.

They also implement one or some browser caching mechanisms in your pages. They are very user friendly and eliminate all the confusion in browser caching methods; no need for code editing.

In the following sections we introduce some of the well known cache plugins for WordPress and explain their options. However you can refer to their producer website for more information.

Where Cache Plugins Can Do Nothing!

Most webmasters use famous advertising companies’ services to show ads on website and monetize their content. Sometimes they embed media from another websites like Twitter, YouTube and many others. When you are receiving a files from external resources (not your domain), there is no cache control over them. If their parent server selected a cache mechanism for them, they would be cached in browser otherwise it is not possible to do it.

Most of the time, resources from 3rd-party servers are the main time-consuming files to load. Neither cache plugins nor theme could help to reduce this time. Use external resources, especially ads, wisely.