What is Caching?
Caching is the process of temporarily storing data in a place - either software or hardware - to speed up its access. This stored data can be quickly retrieved and used again without having to go back to the original source.
Think of caching as a middleman between the end user and the main memory. The cache has a limited amount of space to store data, so it keeps only the most recently or frequently accessed data.
When the user requests data that is already stored in the cache, it can be quickly retrieved from the cache instead of going all the way back to the main memory.
Caching is used in various contexts, such as in devices like smartphones, tablets, and laptops. Apps like YouTube and Snapchat also have their own cache to quickly retrieve data without repeatedly accessing the main memory.
Apart from them, there are four major types of caches through which we can describe the caching process.
Types of cache
The four main types of caches are:
The browser cache is a type of client-side cache that operates on the user's end.
However, when the user searches for the same website or webpage again, the browser fetches these resources from a location closer to the user, which is the cache stored on the device's hard drive.
This process speeds up the retrieval of data and reduces the loading time for subsequent searches.
Whenever a webpage is modified, the previous version becomes outdated, and the browser replaces it with a new version.
The user can also manually clear the cache to remove outdated versions and free up space on their device.
In server caching, data is stored in a cache on the server side, often referred to as a proxy server.
A proxy server acts as an intermediary between the origin server and the end user, reducing the distance between them and improving the performance of the website or application.
Proxy servers not only send requests to the origin server and deliver responses to the client, but they also store data in the form of images, videos, webpages, and other types of content.
This allows them to quickly serve the cached data to the client without having to go back to the origin server every time a request is made.
It is a type of client-side cache that is also known as page cache. When a user visits a website, a copy of the data from the website's persistent memory or database is retrieved and temporarily stored in the website's cache.
This reduces the distance between the user's browser and the server, enabling faster access to the website's information.
In the case of website caching, users will see the latest version of pages that change frequently. On the other hand, data that has not yet been updated will be retrieved from the website's cache.
Overall, website caching improves website performance and speeds up access to website resources for end users.
Search engine cache
Another type of cache is related to search engines, particularly Google, which crawls and saves snapshots of pages it has crawled on its servers.
This cache is different from other types of caches because the cached pages of search engines are displayed only when necessary. During daily browsing, users will typically see live web pages.
In addition to Google, other search engines such as Bing, Yandex, and Baidu also cache pages while crawling.
This caching enables search engines to quickly display search results to users without having to go back to the original website every time a search is made.
Why is caching important?
Caching reduces the time it takes to retrieve data by temporarily storing frequently accessed data closer to the end user, either on the client side or the server side.
This enables the user to quickly access the data without having to go all the way back to the original source every time.
Caching is especially important in high-traffic situations where multiple users are accessing the same data simultaneously, as it can help to reduce the overall load on the system and improve the speed and reliability of data transfer.
Which types of caching play a role in SEO?
Two types of caching can play a critical role in SEO:
Search engine caching
From the SEO point of view, website caching helps improve the optimisation of pages.
Less load time, more crawling
Page load time is the time a page takes to display the full content of the page. When a page is readily available that a user is searching for, it will consume less time to load.
On the other hand, if the same page’s content has to be downloaded repeatedly, it would slow down the loading time.
This way, the page load time affects crawling as Google crawls fewer pages on a website that take more time to load.
Caching can help to reduce page load time by storing frequently accessed resources closer to the end user, this will indirectly increase the optimisation of web pages.
Better user experience, more traffic
Caching can improve the user experience and increase your page's traffic. It is because a user cannot wait for a long time while the page is loading.
The more time your web pages take to load, the fewer users will visit your web pages. It is natural for a visitor to click and stay on a page that loads quickly.
More conversions, more growth
As a result of all these benefits, you can get more conversion rates when users respond to your page’s call to action. It will result in improved growth of your business.
Search engine caching
Search engine caching can also play a crucial role in optimisation.
Retrieve old content
If your website has gone through a problem, in that case, there is a possibility of losing the data; you can use a cached version of pages.
You will find web pages’ content in the form of a cached backup. While not all of the data may be available in the cached version, it can still provide a significant amount of information that can be retrieved.
This can be especially helpful in situations where data loss has occurred or when a website is experiencing downtime or technical issues.
See crawled pages
If you have updated a page on your website, you can check if it has been crawled by looking at the cached version.
However, it is possible that the updated version may not be immediately visible in the cached version. This is not a cause for concern, as the updated version can still be indexed by search engines.
How does Google caching work?
When Google crawls pages of a website, it saves copies of all these pages in the backup to retrieve them if the web page is unavailable for some reason. The copy of a page that Google stores in the cache will be the latest cached copy of that webpage.
It can be called server-side caching because the snapshot or the copy will be saved on the server.
When a user visits a webpage on Google, they will not typically view the cached version of the page. Instead, they will view the live version of the page as it exists on the website's server.
How to view a cached page?
There are two ways you can check the cached version of pages:
You can type the website URL in the search bar.
In SERP, you will find the page’s link and can click the three dots in the top right corner.
A card will be opened with a clickable “cached” button at the bottom.
Clicking on the “cached” button will make you land on the cached version of that web page.
Apparently, this cached page will tell you the date and time when last Google took a snapshot of it. However, it may not be updated information always because this is how John Mueller has responded to a question:
..the date on the cached page is not necessarily the date of the last time we crawled / processed a page for indexing. The cache can be separate from indexing. Sometimes that's clear, if you search for a date and see it in the snippet, but not the cache.
Another way to view a cached page version is to use the “cache:” operator. For this, you can type the web page’s name after the cache: (without space). It is a quicker way to open the cached page.
Drawbacks of caching
The problem of low storage space
Caching involves storing copies of data or files to provide quicker access when requested by the system or user.
However, as more data gets cached, it can consume a significant amount of storage space on your device or server.
When the storage space becomes low, it can negatively impact the overall system performance, forcing you to clear the cache to free up space and maintain normal operation.
The corrupted cache can affect the system
A cache can sometimes become corrupted due to software bugs, hardware failures, or other unexpected issues.
When this occurs, the data stored in the cache may be lost or become inaccessible, causing disruptions in your system's functionality.
Resolving a corrupted cache can be time-consuming, and until the issue is fixed, your system may not perform optimally.
Why does Google cache a page?
Google keeps the pages in storage after crawling them because there can be an error in the page loading, or the webmaster may modify it, which is temporarily unavailable.
In such cases, a user can be presented with a cached version rather than a live webpage.
Sometimes, the website’s speed is slow, or it is down for some reason. In this case, you can visit cached pages.
Can I prevent Google from page caching?
You can prevent Google from caching your page by adding a tag in the HTML code. You may want to do this when you are going to update the page soon. In that case, you can use meta tags to help you with this.
In the <head> section of a specific page, you can add the following code:
<Meta Name="GoogleBots" Content="Noarchive">
This tag will instruct Google not to cache that specific page only. You can do the same with every page you want not to be cached.
Do all the crawled pages get cached?
It is a misconception that all the pages that Google crawls are cached. According to John Mueller’s Twitter reply:
“We don't cache all pages that we index, so that can happen. Sometimes it takes a while, sometimes we just don't cache it at all.”
Can I remove cached pages?
You can remove cached pages using Google Search Console. If you have your site verified by Google Search Console, then you can simply sign in to your account:
In a list of options to the right, you should click “index”, choose “Removal”, then “temporary removal”.
If you click “new removal” in “temporarily remove URL”, a bar will be displayed where you can type your URL.
Selecting “remove this URL only” will remove a specified URL, while selecting “remove all URLs with this prefix” will remove an entire folder.
If you choose “temporary removal”, the current snippet and cached version will be removed for a period of six months. After this period, they will crawl and cache again.
Choosing “clear cached URL” will remove cached pages only, while the original page will remain live.
What can Google’s cached pages indicate?
Page’s slow speed
If the search results show the cached version of your page, it means your page has a slow loading speed. You can work on the errors that are responsible for this.
A competitor’s similar content
By looking at the cached and fresh version of your competitor’s pages, you can assume your competitor's changes to the page.
Caching is an essential process that temporarily stores data to speed up access and improve user experience. Various types of caches exist, such as browser, server, website, and search engine caching.
While caching can enhance SEO and website performance, it can also present drawbacks like low storage space, corrupted cache, and security risks.