These hidden files are typically used by the operating system and the applications you're running to store data that you don't normally need access to—indeed, data that can interfere with the smooth running of your device if it's edited in the wrong way or deleted.

User settings and app configurations are often saved as hidden files, for example. Programs need these files to run, but users don't really need access to them. Hidden file caches are common as well, temporary stores of data to speed up software operations.

This guide comes with a warning then—you edit or delete hidden files from your devices at your own risk, and you really shouldn't have to do anything with these files anyway.

Viewing them can be useful, though, in terms of troubleshooting problems you might be having with your phone or laptop, or for trying to work out exactly where all your digital storage space has got to. Here's how to make these files visible.

Windows
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Some Windows files are more hidden than others.

Screenshot: David Nield via Microsoft

You can view hidden files on Windows by opening up a File Explorer window, switching to the View tab on the ribbon bar, and checking the Hidden items box. Windows will remember your choice until you uncheck the box again, even if you close down File Explorer or reboot your computer.

Hidden files and folders appear with slightly faded out thumbnails in File Explorer, so they're easy to see at a glance, and they'll also show up in searches once you've made them visible. To make a file hidden, or to unhide a file, right-click on it and choose Properties and General: You'll see the Hidden check box at the bottom.

There is another category of hidden file on Windows: Even with the Hidden items box checked, Windows still keeps key operating system files out of sight so they can't be tampered with. To see these files, from the View tab in File Explorer click Options, open the View tab, and uncheck the Hide protected operating system files (Recommended) box in Advanced settings.

macOS
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You can get to the hidden macOS Library folder from Finder.

Screenshot: David Nield via Apple

The easiest way to see hidden files on a computer running macOS is to use the Finder app. Open it up, then use the keyboard shortcut Cmd+Shift+. (that's the period key) to unhide files and folders (or to hide them again). The setting stays in place until you change it (across reboots and so on).

macOS also has an entire hidden folder called the Library folder, where all kinds of user accounts settings and file caches are kept. To see this folder in particular, launch Finder, open the Go menu and pick Go to Folder, then enter "~/Library" as your destination.

Android
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The default Android Files app can show hidden files.

Screenshot: David Nield via Google

If you're looking for files on Android, then the built-in Files app is the obvious place to go: It helpfully splits files up into categories (including downloads and images, for example), so you can find what you're after more easily.

You're not seeing everything by default, though. Tap the menu button (three horizontal lines, top left), then choose Settings: That will lead you to a Show hidden files toggle switch that you can turn on to see files and folders that aren't normally visible (typically files used by apps that you don't really need to know about).

Most third-party file managers for Android also have a hidden files setting available somewhere. In addition, you can go to Storage from the main Android Settings screen to see a breakdown of how much space each app is taking up, including any hidden files that are associated with them.

iOS
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The iOS Files app won't show you hidden files.

Screenshot: David Nield via Apple

iOS is the odd one out in this list, because Apple's mobile operating system doesn't actually let you view hidden files. Hidden files stay hidden, out of reach of users, and remain solely for the use of the OS and the apps running on top of it.

Open up the Files app on iOS, choose On My iPhone, and you can see everything that's saved to the phone itself. The folders you see here will typically be divided up by app, and they hold files relating to user settings, downloads, saved files, and so on.

From the main iOS Settings page you can also choose General and iPhone Storage to see which types of files are taking up room on the device. If you scroll right down to System Data you're able to see how much space these hidden files are using up—but you can't actually view the files themselves.