"Try clearing your cache" is one of the most common tech tips out there, but few people know what a cache actually is. In short, it's a store of copies of data kept close at hand so your device doesn't have to fetch or calculate the same thing twice. Caches make your phone, computer and favorite websites feel fast. In this guide, I'll explain what a cache is, the main types you'll come across, when clearing it helps and how to do it on any device.
What is a cache?
A cache is a small, fast storage area that keeps copies of data you're likely to need again. Instead of downloading the same image, reading the same file from a slower drive or repeating the same calculation, your device grabs the ready-made copy. Think of it like keeping the things you use every day on your desk instead of in a filing cabinet in another room.
Caches exist at almost every level of technology, from tiny memory inside your processor to huge server networks that deliver Netflix and YouTube. They all work on the same idea: keep popular data closer and faster to reach.
How caching works
When a program needs some data, it checks the cache first. If the data is there, that's called a cache hit, and the program gets it almost instantly. If it isn't, that's a cache miss: the program fetches the data from the slower original source and usually saves a copy in the cache for next time.
Because caches are limited in size, they can't keep everything. Older or less-used items get pushed out to make room for new ones, and many cached items also have an expiry time so they don't go out of date. Most of the time, all of this happens automatically and you never notice it.
The main types of cache
CPU cache: L1, L2 and L3
Your processor has its own extremely fast memory built into the chip, split into levels. L1 is the smallest and fastest and sits right next to each core. L2 is larger and slightly slower, and L3 is bigger still and usually shared between cores. This cache stores the instructions and data the processor needs next, because even fast RAM is far slower than the processor itself. A bigger cache can noticeably help in games and heavy apps, which is why chipmakers advertise it, for example with AMD's X3D gaming processors.
Browser cache
Your web browser saves parts of the websites you visit, such as images, fonts, stylesheets and scripts. The next time you open the same site, it loads much faster because the browser doesn't need to download everything again. This is also the cache people usually mean when they suggest clearing it to fix a website that looks broken.
App cache on phones and computers
Apps store temporary files like thumbnails, downloaded images, map tiles, and video or music previews. Social media and streaming apps can build up caches of several gigabytes. App caches can be rebuilt at any time, so clearing them frees space without deleting your account or settings, although the app may be slower the first time you open it afterwards.
Storage drive cache
SSDs and hard drives use cache too. Many SSDs have a DRAM cache that keeps track of where data is stored, plus a portion of fast SLC cache that absorbs large writes. When you copy a very big file and the speed suddenly drops halfway through, that's usually the SLC cache filling up. High-end drives like the Samsung 990 PRO have a large cache and keep speeds high for longer, and our external SSD ranking covers portable options.
GPU and game caches
Graphics cards and games keep shader caches, which store pre-compiled graphics code so games don't have to rebuild it every time. If a game stutters right after an update, it's often rebuilding this cache, and the stutter usually disappears after a while.
DNS cache
When you type a web address, your device has to look up the server's IP address using DNS. To save time, your device, browser and router remember recent lookups. If a site has moved to a new server, an outdated DNS cache can stop it loading until the old entry expires or you clear it.
Server and CDN caches
Websites and streaming services use caches on their side too. Content delivery networks, or CDNs, store copies of videos, images and pages on servers around the world, so you get them from a nearby location instead of a distant data center. That's why a popular YouTube video starts instantly, and why changes to a website sometimes take a little while to appear for everyone.
Cache vs RAM vs storage
These terms often get mixed up, so here's how they compare:
| Type | Typical size | Speed | What it stores |
|---|---|---|---|
| CPU cache | Kilobytes to a few hundred megabytes | Fastest | Instructions and data the processor needs right now |
| RAM | 8 to 64 GB in most devices | Very fast | Open apps and the files you're working on |
| SSD or hard drive | 256 GB to several TB | Much slower than RAM | Your system, apps and files, kept when the power is off |
| Browser and app cache | Megabytes to several GB | As fast as your storage | Copies of images, scripts and media you've loaded before |
| CDN cache | Huge server networks | Faster than the original server | Copies of websites, videos and downloads close to you |
When should you clear your cache?
Most of the time, you shouldn't. A cache exists to make things faster, and clearing it just forces your device to download or rebuild everything again. It's worth doing in a few specific situations: when a website looks broken or shows old content, when an app keeps crashing or behaving strangely after an update, when you need to free up storage space quickly, or when you're troubleshooting a login problem. Clearing it on a schedule "to keep things fast" usually does the opposite.
How to clear the cache in Google Chrome
On Windows, Mac, Linux and ChromeOS: press Ctrl + Shift + Delete, or Command + Shift + Delete on a Mac. Choose a time range, tick "Cached images and files" and untick cookies and history if you want to stay signed in, then click Delete data.
On Android: open Chrome, tap the three-dot menu, go to Delete browsing data, select "Cached images and files" and tap Delete data. To clear an app's cache, go to Settings, then Apps, choose the app, open Storage and tap Clear cache. Avoid "Clear storage" or "Clear data" unless you want to reset the app completely.
On iPhone and iPad: in Chrome, tap the three-dot menu, then Delete browsing data, and select "Cached images and files". For Safari, go to Settings, then Apps, then Safari, and choose Clear History and Website Data. iOS doesn't have a cache button for other apps, so to clear an app's data you can use Offload App or delete and reinstall it.
Clearing the cache in other browsers
Safari, Edge, Firefox and Opera all have the same option in their privacy or history settings, usually called "Clear browsing data" or "Clear history". In most of them, the Ctrl + Shift + Delete shortcut opens it directly on a computer. Look for the option that mentions cached images and files, and leave cookies and passwords unticked unless you want to sign out of websites.
Hard refresh vs clearing everything
If only one website looks wrong, you don't need to clear your whole cache. A hard refresh reloads the current page and ignores the cached files. On Windows and Linux, press Ctrl + Shift + R or Ctrl + F5. On a Mac, press Command + Shift + R. It's quicker and you won't slow down every other site you visit.
What clearing the cache doesn't do
Clearing the cache won't remove viruses or malware, make an old device permanently faster or fix problems caused by your internet connection. It also won't delete your files, photos or accounts. If you're short on space because of photos and videos, clearing the cache is only a temporary fix, and moving them to cloud storage like Google Drive will free up much more. Our guide on where to store your phone photos covers the best options.
Cache and privacy
Cached files can reveal which websites you've visited to anyone with access to your device, so clearing the cache and history makes sense on a shared or public computer. Using a private or incognito window is even easier, because it doesn't keep the cache after you close it. Keep in mind that cookies, not the cache, are what keep you signed in and let sites track you, so clearing only the cache won't sign you out or stop tracking.
Quick troubleshooting checklist
Website looks broken or outdated: do a hard refresh first, then clear that site's data.
App crashes or freezes: clear the app's cache, then update or reinstall it if needed.
Storage almost full: clear caches of the biggest apps, then move photos and videos elsewhere.
Site won't load after a change: restart your router or clear the DNS cache.
Game stutters after an update: give it time to rebuild its shader cache.
Final thoughts
Caches are one of the main reasons modern devices feel fast, and in most cases it's best to leave them alone. Clearing the cache is a useful fix when a website or app misbehaves or you need some free space quickly, but it's not a regular maintenance task. Start with a hard refresh or a single app's cache before you wipe everything.
