What Is Caching Data and How It Works? | Fortinet (2024)

What is caching data and how does cache work?

Caching Dataor data caching is a process that stores multiple copies of data or files in a temporary storage location—or cache—so they can be accessed faster. It saves data for software applications, servers, and web browsers, which ensures users need not download information every time they access a website or application to speed up site loading.

Cached data typically includes multimedia such as images, files, and scripts, which are automatically stored on a device the first time a user opens an application or visits a website. This is used to quickly load the application or website’s information every time the user subsequently opens or visits it. Caching is a good solution for the von Neumann bottleneck, which looks at ways to better serve faster memory access.

A Domain Name System (DNS) caches DNS records to perform faster lookups, content delivery networks (CDNs) use caching to reduce latency, and web browsers cache requested Hyper Text Markup Language (HTML) files, images, and JavaScript to load websites faster. For example, when a user visits a website for the first time, an application or browser retains information to help them access it faster and more efficiently.

Cached data works by storing data for re-access in a device’s memory. The data is stored high up in a computer’s memory just below the central processing unit (CPU). It is stored in a few layers, with the primary cache level built into a device’s microprocessor chip, then two more secondary levels that feed the primary level. This data is stored until it's time to live (TTL), which indicates how long content needs to be cached for, expires or the device’s disk or hard drive cache fills up.

Data is typically cached in two ways, through browser or memory caching or through CDNs.

1. Browser and memory caching:Memory caches store data locally on the computer that an application or browser runs on. When the browser is active, the resources it retrieves are stored in its random access memory (RAM) or its hard drive. The next time the resources are needed to load a webpage, the browser pulls them from the cache rather than a remote server, which makes it quicker to retrieve resources and load the page.
2. CDNs:Caching is one job of a CDN, which stores data in geographically distributed locations to reduce load times, handle vast amounts of traffic, and protect against cyberattacks. Browser requests get routed to a local CDN, which shortens the distance that response data travels and transfers resources faster.

When a user visits a new website, their browser needs to download data to load and display the content on the page. To speed up this process for a user's future visit, browsers cache the content on the page and save a copy of it on the device hard drive. As a result, the next time the user goes to that website, the content is already stored on their device and the page will load faster.

Cache memory offers extremely low latency, which means it can be accessed quickly. As a result, it speeds up loading the second time a user accesses an application or website. However, a cache cannot store a lot of memory, so it only stores small files like images and web text.

Data can be cached in many ways, but it is typically reliant on the website’s owner to set a "header," which tells a device that data can be cached and for how long. This instructs a user’s browser what information to download and where to store the temporary files. The user can then create policies and preferences around what data they cache and even clear their whole cache to reduce the amount of data stored on their device.

Caching data is important because it helps speed up application performance and increase efficiency. It stores data locally, which means browsers and websites will load faster because access elements such as homepage images have previously been downloaded.

Internet users will typically leave a website that loads too slowly, which makes caching vital for website owners to improve user experience and encourage people to use their site. It is also important for online tools like Google Docs, which enable users to access and save their documents online.

However, there are downsides to caching data. Caching can improve browser performance, but it also risks users’ confidential or sensitive information being exposed to cyber criminals. Caching data could result in authentication data, browsing history, or session tokens being vulnerable, especially if a browser is left open or if another user has access to it.

A cache can be cleared in different ways depending on the device being used. Cached data can be cleared across all web browsers using the below processes:

1. Apple Safari:Open Safari and select the "History" option, then "Clear History" to remove all the data saved on the browser. It will then load a drop-down menu that enables a choice of data from the last hour, last day, last two days, or the user’s entire history, which will delete their entire browsing history, all their cookies, and their entire browser cache. Safari users can also select individual sites on their history, right-click them, and delete.
2. Google Chrome:Open Chrome and select the Settings icon, represented by the three vertical dots in the top-right corner of the browser. Select the "More tools" option, then "Clear browsing data." On the next page, select the checkboxes for cached images and files, cookies, and site and plug-in data. Then use the options to choose how much data to delete, from the past day through to "the beginning of time." With that done, select "Clear browsing data." This process works for Chrome on computers and on Android and iOS devices.
3. Internet Explorer:Open Explorer and select "Tools" in the gear Icon, then select "Safety" followed by "Delete browsing history." Select the data to be cleared by ensuring all of the relevant boxes, including Cookies and Temporary Internet Files, are checked, then select "Delete." The browsing history menu can also be opened by holding Ctrl, Shift, and Delete at the same time.
4. Mozilla Firefox:Open Firefox and click the Library button, then select "History" followed by "Clear Recent History." Select the time range of cached data to clear, then click the arrow positioned next to "Details" to select the information that will be cleared. Select "Clear Now" to clear the cache.

Cached data can also be cleared on mobile devices by deleting the data stored by apps. Mobile cached data can be cleared using these processes:

1. Android devices:Android users can clear the cache on their device to free up storage space. Open the Settings menu, then open "Apps" or "Applications," find the application to clear the cache or data of and select "Storage." This will show the amount of storage being used by the application and provide the option to clear the data.
2. Apple iOS devices:Apple users can also clear the cache on their device to delete data that eats up storage space. Open the Settings menu, then the "General" option. Within that, go to "Storage & iCloud Usage," then open "Storage" and select "Manage Storage." Select an application in the list, then go to "Documents & Data." If the app is using more than 500 MB of space, then reinstall it to clear space.

Clearing cached data deletes information stored in the CPU cache. This can be helpful if a user is running low on storage on their device or if they have information stored for websites they no longer use.

Clearing the cache can also correct an incorrectly loading page but slow down page load times of previously visited websites. It results in every website loading as if the user has never visited it before and could delete stored data, website logins, and more, so users must be careful about what they delete before going ahead with clearing cached data.