You should never touch these default Windows files and folders! Here’s why
In addition to your private files and folders, Windows takes up a lot of space on your computer. With a bit of searching, you can find hidden Windows caches that are safe to clear and use other folder tricks.
However, there are several Windows default files and folders that you should leave alone. Messing with these could result in an unstable system, loss of data, or other horrible consequences. Let's discuss the places that most users shouldn't visit in their travels through the Windows file system.
1. Program Files and Program Files (x86)
Located at C:\Program Files and C:\Program Files (x86)
Whenever you install software, you usually open up an EXE file and run through an installation process (if not, you're using a portable app). During this time, the app is creating an entry for itself in the Program Files folder, adding Registry values, and doing other tasks that it needs to work properly on your system. Thus, if you head into the Program Files folder, you'll find folders for most programs you have installed.
With rare exceptions, you should never need to touch a program's data in these folders. They contain DLL files and other configuration information that the program needs to function. If you start messing with these, you could screw up an app and have to reinstall it. Further, when you want to uninstall some software, the proper way to do it is via the Programs and Features menu in the Control Panel or using a third-party alternative.
Deleting an app's folder from Program Files doesn't remove other references to it on your system and thus is not a clean uninstall. This contrasts from how macOS handles uninstalling — all you have to do on a Mac is drag an app to the Trash to remove it.
If you're using a 32-bit version of Windows, you can only install 32-bit software and thus you only have one Program Files folder. On 64-bit Windows versions, you'll see an additional Program Files (x86) folder. Your computer stores 32-bit software there, while 64-bit compatible software goes in the standard Program Files folder.
Located at C:\Windows\System32
Nearly everything in the C:\Windows folder could fall under this list, but the System32 folder deserves special attention. It holds hundreds of DLL files that are essential to your computer running properly.
Some examples include the service that handles sound on your PC, files that are essential to booting into Windows, resources that make fonts display correctly, and more. Also contained in this folder are executables for default Windows programs. For instance, Calc.exe launches the Calculator, and MSPaint.exe launches MicrosoftPaint.
You don't really have a reason to ever visit System32, but it's been the topic of a long-running internet joke. Some people like to mess with novice users and tell them that System32 is a virus, or that deleting it will make their computers run faster.
Obviously, since the folder is critical to Windows functioning, messing with it could mean having to reinstall Windows.
3. Page file
Located at C:\pagefile.sys (Note that you won't see this file unless you go to File Explorer Options > View and uncheck Hide protected operating system files. We don't recommend doing this, though.)
Random-access memory, or RAM, inside your computer is responsible for temporarily holding open programs. When you open an instance of Word, it's placed in RAM for quick access. This is why having more RAM allows you to run several programs concurrently (check out our guide on RAM for more background).
If your physical RAM starts to fill up, Windows uses what's called a page file or swap file. This is a dedicated portion of your hard drive that acts like RAM. If you have enough RAM in your computer, you should rarely ever see the page file take effect. However, relying on it often will affect performance, as hard drives are much slower than RAM (especially if you don't have a solid-state drive).
Whenever you use a tool to show what's taking up space on your computer, chances are the page file takes up several gigabytes. You might be tempted to disable it to save space, but that's not a good idea. Without a page file, when your RAM maxes out, programs might start crashing instead of swapping into that extra memory.
Windows lets you manage that virtual memory if you really must, but most users should let the operating system manage this automatically. If you've got memory problems, the solution is to add more RAM to your system.
4. System Volume Information
Located at C:\System Volume Information (It's hidden if Hide protected operating system files is checked.)
Another large folder that doesn't have an obvious purpose, the System Volume Information folder actually contains several important Windows functions. In fact, when you try to access it, Windows will give you an Access Denied error.
This folder contains the System Restore points which your computer creates so you can jump back in time. To decrease this folder's size, you can type Restore Point into the Start Menu and click Create a Restore Point. In this window, click your C: drive and choose Configure. You can slide the Max Usage bar to a certain amount to reduce the space that System Restore uses, but beware that this decreases your options if you need to do a restoration in the future.
Aside from restore points, System Volume Information also includes data that Windows uses to index your drives. Without this, searches that take an instant would slow to a crawl. It also holds the Volume Shadow Copy service that's required for file backups.
Like other important folders, you should stay away from this one. Don't try to gain access to it or make changes — Windows needs its contents for healthy performance and there's no reason for you to edit it.
Located at C:\Windows\WinSxS
WinSxS stands for Windows Side By Side and was created in response to an issue that made working with Windows 9x versions a pain. The colloquial term "DLL Hell" describes the problems that arise when dynamic link library (DLL) files conflict, duplicate, or break.
To fix this, Microsoft started using the WinSxS folder to collect multiple versions of every DLL and load them on demand when Windows runs a program. This increases compatibility, such as when a program needs access to an older DLL that's no longer part of Windows.
The longer you use Windows, the bigger this folder becomes. As you might guess, trying to pick and choose files to delete out of this is a bad idea. You shouldn't ever visit this folder directly; instead, use the Disk Cleanup tool to clear out unneeded files.
Windows keeps many folders hidden for a reason. The average user doesn't have any reason to touch these resources directly, as Windows provides ways to manage them that won't risk damage to your system. When you see a file in a hidden folder that you don't know about, it's best to Google it first so you don't get into trouble. Make sure you're keeping good backups so you can recover if something ever goes wrong!