What is caching and how is it done?

Caching is the process of storing copies of data and entire files in a temporary storage location, which is called the cache. There are a few reasons to set up caching, but the most common one is so that end users can access data faster.

What is caching?

When you visit a website for the first time, your browser sets aside some storage space that can be used to download and retain the pages layout, images, and sometimes even the scripts that make the site function correctly.

If you had to download a fresh copy of this data on every visit, it would be a drain on everybody’s resources: You would use bandwidth and processing power, and so would the web server. The loading process might drag on for a while.

Instead, what if you just checked to see if there are any updates to the page, downloaded only the new data, and just used the information that you stored last time to fill in everything else?

That’s where caching comes in. A browser caches the content of a web page that rarely changes and saves a copy of it to speed up the loading process on the next visit.

Caching is temporary local storage for website elements such as HTML, JavaScript, CSS, or images. This is a considerable advantage when it comes to search engine optimization (SEO). If a website doesn’t load quickly, people leave. That drives up abandonment rates, and drastically reduces the chances of the website being recommended to anyone else. That’s why Google keeps metrics on how responsive a site is. The slower the site, the less likely it is to be ranked highly in search. In other words, caching improves both browser performance and user experience.

Are there other kinds of caching?

Browser caching is just one way that a user’s network experience is improved by keeping copies of data in smart locations. Here are a few other ways that this process is used:

Network route caching is done on switches and routers so that your ISP and internet backbone providers don’t have to look up addresses and network paths constantly. They keep local routing paths and address resolutions in tables, so that the most common connections can be made instantly.

Regional caching, also known as mirroring, means that a complete copy of an application or website can be stored on several different continents to serve a worldwide audience.

Other kinds of caching are used to improve live streams, to help balance the load of popular websites between multiple servers and databases, and to improve mobile device data usage.

How does browser caching work?

Browser caching puts website data in temporary storage, known as cache. This can happen in one of two ways:

1. Browser and memory caching is when data is stored locally on a computer, assuming it has the right permissions. Browser data is stored in random access memory (RAM) or on a local drive. Next time a user visits the site, the browser pulls data from the cache assuming nothing has changed. Any files that have changed are downloaded again, replacing the existing copy in the cache. Browser caches can be manually emptied or are automatically emptied once full.
2. Content delivery networks (CDNs) use regional caching methods, like we talked about in the last section. This means your requests only need to travel a short distance, no matter where the main website is hosted. CDNs can also help the site defend itself against attacks that are meant to flood the website with fake requests (DDOS attacks).

Not everything is cached, of course. The server can include a tag on the data called “no-store” that tells the browser to never cache that particular string. And the user can prevent caching on certain websites, if they wish, by going into their browser’s site preferences.

Other benefits of caching?

We know that caching reduces bandwidth usage and improves the user experience. But what else does it do?

The memory used for cache is fast. Server performance is improved when the cache deals with a request; it is much better than accessing a drive. More efficiency means lower server costs. It also reduces the load on the backend and minimizes the risk of crashes.

There are some downsides to caching. Because it stores user data, improper caching can expose confidential information to cyber criminals. An unencrypted cache can be a treasure trove if your device is stolen. This is why device security, whole drive encryption, and mobile device encryption are so important.

How can you tell when caching is being used on the server side?

Caching is set up by your system administrator if you run your own server, or by the settings on your hosting site’s control panel. Apps can be used to fully optimize your website for SEO. Load times, the site’s search engine ranking, and other details can be analyzed to find the best caching strategy. This is one of the best ways to speed up WordPress. Consider using one of the top WordPress caching plugins to get started.