What is a cache? A complete guide to caches and their important uses on your computer and phone
- A cache is a special storage space for temporary files that makes a device, browser, or app run faster and more efficiently.
- After opening an app or website for the first time, a cache stashes files, images, and other pertinent data on your device.
- Cached data is used to quickly load an app or website for every subsequent visit.
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If you've ever troubleshooted something on your computer or cleaned up your browsing history, you've most likely come across advice related to the cache (pronounced "cash").
Most likely, you've been prompted to clear it.
But what is a cache, and why would you want to do that? Here's everything you should know about caches and why they're crucial to modern technology.
What is a cache?
A cache is a reserved storage location that collects temporary data to help websites, browsers, and apps load faster. Whether it's a computer, laptop or phone, web browser or app, you'll find some variety of a cache.
A cache makes it easy to quickly retrieve data, which in turn helps devices run faster. It acts like a memory bank, making it easy to access data locally instead of redownloading it every time you visit a website or open an app.
In terms how this affects your day-to-day, there are three main areas where caches play a major role:
Devices and software
Caches are found in both software and hardware. The CPU, or central processing unit - the core component responsible for processing information from the software in your desktop computer, laptop, smartphone, or tablet - has its own cache.
A CPU cache is a small block of memory that's designed to help the CPU easily retrieve frequently used information. It stores data that your device's main memory uses to execute instructions far more quickly than if it had to load every bit of information only when it was requested.
- Web Browsers
Every web browser, whether it's Microsoft Edge, Chrome, Firefox, or Safari, maintains its own cache.
For example, when you visit Amazon, it downloads all the images associated with product pages you visit, the HTML and other script files needed to render the pages, and personalization information, such as your login information, and the contents of your shopping cart.
That's why if you clear your browser cache, retail sites will require you to log back in and rejigger your settings.
Apps typically maintain their own cache as well. Like browsers, apps save files and data they deem important so they can quickly reload the information as needed. Every app is different, though, and so the kind of data it caches will vary, but might include images, video thumbnails, search history, and other user preferences.
Benefits of caches
From a user standpoint, there are three main benefits to caches, including:
- They make everything run faster. The key benefit of a cache is that it improves the performance of the system. By storing local copies of web site files, for example, your browser only needs to download that information the first time you visit, and can load the local files on subsequent visits.
- They save data. To help improve performance, apps store recently and frequently used data to the cache. Not only does this allow everything to run faster as previously mentioned, but in some cases it can allow apps to work "offline." For example, if you don't have internet access, an app can rely on cached data to continue to work even without a connection.
- They store data for later use. There's a lot of efficiency in only downloading files once. If a copy of a file is stored in the cache, then the app doesn't need to waste time, battery power, and other resources downloading it a second time. Instead, the app only needs to download changed or new files.
Downsides of caches
While modern software depends heavily on the use of caches, they have some disadvantages as well:
- They can take up a lot of storage space. In principle, a cache is a small repository of files used by an app. But some caches can grow exceedingly large and limit the free space on your device. Clearing the cache can erase the files and recover a large amount of memory.
- A corrupted cache can cause the app to behave badly. If there's something wrong with a file stored in the cache, it can cause the app to display data incorrectly, glitch, or even crash. That's why a common remedy for browser issues is clearing the cache.
- Caches can prevent apps from loading the latest version of a web page or other data. In theory, apps are supposed to only use the cache to display files unchanged since the last visit. That doesn't always work, though, and sometimes the only way to see the latest version of a web site or other info is to clear the cache, so the app is forced to download everything anew.
What does it mean to clear the cache?
Given the downsides of cache, it makes practical sense to clear your cache as part of regular maintenance. In addition to corrupted files, if a cache gets too large, or if your computer starts to run low on storage space, these issues can also affect your PC's performance.
The solution is to "clear the cache," which deletes the files stored in the cache.
If a cache can be cleared by you, the user, the program that owns the cache generally makes that option available somewhere in its settings menu.
We've also written extensively on how to clear the cache on different devices. Here's how to clear the cache on:
The advantages of clearing the cache include freeing up previous storage space on your computer and eliminating any files that might be causing it to misbehave.
Unfortunately, clearing the cache also eliminates the files that are designed to make your computer run more efficiently. For example, clearing a browser cache typically means you'll have to log into all your favorite websites all over again, and you'll lose any special customizations or personalization you had there, including the contents of shopping carts or baskets.
But if you're experiencing problems with your Mac, PC, or mobile device, clearing the cache is worth it.
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