We enable caching (and other optimisation) on the majority of our client’s websites. We often get asked, but why? And what exactly is caching? In this article, we’ll cover those questions and more.
Side note: this is a simplified overview, rather than an in-depth dive.
Why is caching used?
The two main reasons caching is used is to:
- Drastically improve the speed and performance of websites.
- Reduce the server and browser resource consumption.
What is caching?
Caching is a form of website optimisation where static versions of your website’s pages are generated, stored and subsequently served more efficiently.
Within the caching umbrella you have two main types: server and browser.
Server caching
Server caching takes place, as you would imagine, on the web server.
Web pages in content management systems like WordPress are typically generated dynamically.
Dynamically means when a web browser (end user) makes a request to the server for a particular web page, the server has to compute a bunch of functions and database queries required to generate the file (web page) and then send that file to the browser.
As you can imagine, this takes time. That’s where caching comes in.
Caching stores the generated file for a web page and keeps it ready for the next visitor. This ‘cached’ file can then be served (almost) instantly, without having to carry out all the time consuming functions and database queries.
*often stored on servers around the globe creating a Content Delivery Network (more on that below).
Where is that file stored? Sometimes it’s stored directly on the web server itself. However, most of the time caching is combined with a Content Delivery Network (CDN).
We’re going to be writing an article on CDNs in the near future, but here’s an overview…
Content Delivery Network (CDN)
Caching goes hand in hand with Content Delivery Networks.
CDNs are a collection of servers (often called nodes), dotted around the world that store content such as images and files so they can be accessed closer to the end user (requesting browser).
This means that users in other countries can access servers (nodes) of the stored content in a closer physical location. Ultimately, this should mean the data (web pages) have less distance to travel.
For example
Let’s say the original web server is based in the UK. The hosting makes use of a CDN with nodes all around the world, including the US. When an end-user from the US visits the website, rather than connecting to the original server in the UK, it connects to the node in the US.
Browser Caching
Browser caching happens on the client’s side – that’s your side.
It works by storing cached files in the application so they can be retrieved almost instantly without having to make a request to the web server for the file.
Each browser treats caching slightly differently and has different rules for caching different file types. On top that, often web servers will instruct browsers how long files should be cached for.
Side note: here’s an article on clearing your browser cache.
Are there any downsides of caching?
There can be issues of seeing out of date content. Whilst there are solutions and redundancies in place to minimise this, it can happen.
If you are experiencing any issues, please get in touch with us.