website caching

Website caching is an important aspect of website performance and optimization. For all the benefits web caching offers, it can sometimes create frustration for web professionals and confusion for clients. Here’s an overview of how different types of website data caching affect what you see online.

What is website caching?

Website caching is a way of storing frequently accessed web page data in order to speed up the website loading process. When a user visits a cached website, the web browser will first check to see if there is a cached (saved) version of the page available before requesting the page from the server. If a cached version is available, it will be loaded instead of the server-side version, resulting in a faster loading time.

How does caching work?

Caching can be performed by the server, by the client (your browser—Chrome, Safari, etc.), your web hosting provider, a third-party service, such as Cloudflare, and your ISP. In most instances, a website is cached with several of these types simultaneously. This layering works together to boost website speed. Each caching tool will typically have a time limit before refreshing, ranging between a few hours to as much as a day, sometimes more.

Types of website caching:

Browser caching is a mechanism for temporarily storing files on a user’s computer. When a user visits a website, their web browser (Chrome, Safari, Firefox, etc.) will save data files to their computer’s cache. This cached data can then be used the next time the user visits the site, which improves load times. Browser caching delivers faster page loads and reduced bandwidth usage for both website owners and visitors. If you’ve ever experienced a technical issue with a website, you may have been advised to “clear your browser cache”. This can be annoying, as you’ll really notice the difference in speed and convenience once that cache is cleared out!

Server-side caching (your web host):  There’s several tools your website host may use to store frequently accessed web pages on the hosting server. When a user visits a cached website, the server will serve the cached version of the page instead of generating a new one. This speeds up the website loading process, but it also means that any changes made to the website will not be reflected in the cached version until it is updated.

Third-party service caching: Also known as a content delivery network or CDN, third-party caching services can be extremely beneficial for businesses that have a national or global reach. By caching static content on a CDN, businesses can ensure that their website loads efficiently for visitors no matter where they are in the world. Additionally, a CDN will often have security features, such as protection from distributed denial of service (DDoS) attacks and other malicious activity.

ISP DNS and website caching:  Clients are often surprised to learn that that their ISP (Verizon, Comcast, etc.) can affect what they see online. One of the ways in which ISPs deliver fast service is by caching DNS entries. (DNS is the system that converts website names into IP addresses, and it can be slow at times.) By caching DNS entries, your ISP can save you a trip to the DNS server and speed up your web browsing. While the major ISPs are frequently refreshed, when current DNS records aren’t updated, it can be quite frustrating, as you don’t have any control over it. The methods to clear a DNS cache can be disruptive and need some technical know-how. Fortunately, this is a less common issue these days.

In addition, an ISP can store a copy of website data on its servers. When you type in a website’s address, your ISP will check its cache before sending a request to the website’s server. If the website is cached, your ISP will serve you the cached version instead of retrieving it from the server again. This can be helpful if the website gets a lot of traffic, because it helps reduce network congestion and speed up loading times.

What a website visitor can do about caching:

If you suspect that you’re not seeing the latest content changes on your website (or any website you’re viewing), the first and quickest thing to try is to simply check the page in an alternate browser. For example, if you normally use Firefox, try opening Chrome instead and see if you can see your page updates.  If that doesn’t work, then try your browser’s “incognito” or “private” mode. If you’re not in a hurry, just check the page later, as all caching will usually refresh itself in about a day or less.

If those fail, you’ll want to clear your browser cache data. While this can be a pain in the short-term, an occasional browser clean-out will help keep a tidy web environment and improve its overall performance. Here’s quick how-to links for each of the major browsers:

What your webmaster can do about caching:

If all else fails, ask your webmaster to check and clear your web hosting caching and/or CDN tools – and there may be several of these layered on your website. This should only be needed when critical updates are being made to your website. When I make changes to a client’s website, I do a quick cache clear before sending to the client for review.

The takeaway:

In summary, website and DNS data caching is critical to your website’s performance and speed. It’s an essential tool for webmasters, as it improves performance and reduces server load. Implementing various types of caching tools such as browser cache, page cache, object cache and database query caching, webmasters are able to enhance overall user experience of their websites. Being aware of how caching works and how it impacts what you see online is a helpful way to better understand how your website works.

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