The world of the Internet can be confusing for those who are unfamiliar with the terminology. One term that does cause confusion is “cache”. Some people may think of the cache behind their browser that they frequently empty to gain disc space. Others will think of the cache that a search engine holds – really just a copy of the web page in question. Most bloggers are familiar with the term cache, especially if they are using one of the popular caching plugins.
In a way, each of these refer to similar processes, the difference being the way they are handled. In a browser, it will hold a copy of a web page in case it is needed again. You can see the affect of a browser cache by visiting a slow-to-load web page, clicking on a link, then hitting the back button. The first page will reappear very quickly, and the reason for this is that the page is stored on the computer, not called from the websites server.
The same is true of a search engine cache. The search engine keeps a copy of a page which allows users to get a quick view of the page before clicking through to the site. Webmasters frequently check this cache to see if the search engine has the latest version of their page.
When it comes to blogs and content management systems like WordPress or Drupal, there are special plugins or modules that do a similar job. On those sites, a copy of a page is held in a cache so when a user arrives the page is loaded from the cache. This significantly improves page load times while reducing bandwidth and server time.
For static websites, a different form of caching exists, although it has a similar effect. Rather than storing a mirror image of a web page, server-side caching modifies data sent between a website and a client, generally a browser. The information modified includes data such as the last time a page was updated. The client (browser) will compare that data to determine whether or not the content has changed since the last visit. If the content has not changed, then the browser will republish what is stored locally rather than calling for a fresh page.
From an SEO perspective, any action that helps to improve page load times will be a bonus. Search engines are now using page load speed as a ranking factor with fast pages gaining a boost at the expense of slower pages. Caching, along with page compression, are two tactics that professionals look at first. In most cases, they are quick and easy to implement, and most importantly, are available at no cost. The positive effect for both users and search engines is instant – there are not to many SEO tactics that have such an instant effect.