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Caching Explained

When working with website developers you will at some point hear about cache/caching, if we have directed you here then it is with the hope of explaining something which even we can struggle to understand at times.

One of the best explanations of caching I came across was from a speaker at a WordPress conference. The speaker asked the audience “What’s 3,485,250 divided by 23,235 ?”

*The speaker was Peter Chester

Everyone fell silent.

Some people pulled out calculators to do the maths, and finally someone yelled out the answer after a few seconds.

Then the speaker asked the exact same question again. This time everyone was able to immediately call out the answer.

This is a great demo of the concept of caching.

The initial time-consuming process was done once, then after that, when the same question was asked, the answer was readily available, and delivered much faster.

When applied to the context of your website, this translates to the ability to deliver a webpage with a super-fast response time without having to do all the time-consuming processing, every time the page loads.

The first visitor to a particular page on your site is “asking the question” and your server provides the answer. The next time a visitor goes to the same page, ie. “asks the same question”, your server can provide the answer, i.e the web page, much faster.

When we are working on your website we will change the code and when we do this we have then effectively changed the question and therefore changed the answer.

The problem then arises that it is not so easy to convince a room full of people that the answer they knew before has now changed.

To add to our problems some of the people in the room have told other people the old answer. People that are not in the room that we have no control over.

What I mean by "other people" is that your own computer’s browser will also save cache information and will continue to show your site from the previous version.

So this is the situation we have, where we have changed code on your website, confident we have completed work on the site, yet you may not be able to see any evidence of that work.

Refreshing the browser a few times can often be the solution but sometimes caching is stubborn and it may just be a case of waiting.

Can’t we just turn it off?

Unfortunately the downside of caching is something we must tolerate; simply because the mild inconvenience of changes not being immediately visible is far out weighed by the increased speed and efficiency of your website and server.

So there we are, I hope that helped you to understand
what caching is and how it affects what you see on websites.

Here are some other resources which may help you out:

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UK based WordPress Development Specialists

Thanks to Peter Chester for his talk