Most people know that the Disk Cleanup utility in Windows can help reclaim storage space on a PC. With a single click, the app scans your machine and shows you a long list of things you can delete. Some of these options are self-explanatory, but others are not. You certainly don't want to delete something important by mistake and end up facing a blue screen of death. This list covers the types of files that commonly show up in Disk Cleanup and tells you whether they are safe to delete.
Delivery Optimization Files
These files can easily take up gigabytes of storage, yet it isn't obvious what they actually are. Disk Cleanup only says that deleting them is safe if you don't use them. But what are they?
Essentially, Delivery Optimization files are Windows update files. When Microsoft releases an update for Windows, many PCs are set up to download it automatically. That can put a strain on Microsoft's servers.
To make sure everyone gets updates in a timely way, individual Windows PCs are set up to store copies of those update files and share them with other Windows PCs. It works much like torrenting a file. Unfortunately, these files are saved on your PC's drive, where they take up space. The good news is that you can safely delete them.
Language Resource Files
These files relate to the various language packs that come with Windows. They keep language-related processes accurate while you use your PC. The files include several languages, dictionaries, spelling and grammar rules, and keyboard layouts. If you're confident you will never need another language on your system, you can delete them. Keep in mind, though, that doing so doesn't recover much space, so you may as well leave them alone.
System Error Memory Dump Files
System Error Memory Dump files are created whenever your machine hits a major error or the dreaded blue screen of death. Windows keeps only one of these dump files at a time, overwriting it each time you have a crash. The files can be quite large because they contain a lot of data.
With the .DMP extension, dump files can be used to diagnose the problems a system runs into. Even so, the average user probably doesn't care to dig into the technical reasons behind a malfunction. You can, however, send them to Microsoft for analysis, to identify the bug and possibly fix it in a future update. Otherwise, go ahead and delete them.
System Error Minidump Files
System Error Minidump files are like the annoying little siblings of System Error Memory Dumps. They also provide data that can help programmers or developers debug problems the system has run into. If that doesn't interest you, delete them.
Temporary Files
Temporary files are created by the apps on your PC. Apps use them to run more efficiently. Usually, they are deleted automatically, but you can remove them manually if you like.
Temporary Internet Files
When you browse the web, some bits of data are stored on your computer so those sites load faster the next time you visit them. This is called the browser cache. You can choose to clear the browser cache, but you may want to reconsider. Deleting these files can actually slow down your browsing experience. Besides, the deletion isn't permanent. As you browse, your browser collects these bits again.
Thumbnails
When you open a folder containing files such as documents or photos, Windows creates a thumbnail image so you can quickly identify each file. You can delete these thumbnails with Disk Cleanup if you want. But if you open a folder containing these files again, Windows will recreate the thumbnails.
Windows Error Reporting Files
Windows Error Reporting (WER) is a Windows feature that dates back to Windows XP. When a program crashes or the system runs into a serious problem, a .WER file is created. These reports collect data about the system's hardware and software configuration and what happened. They are sent automatically to Microsoft for review. Archived .WER files show up when you run Disk Cleanup. These reports have already been sent to Microsoft, so unless you want to try to solve the problem yourself, you can safely delete them.
Windows ESD Installation Files
You probably won't come across Windows ESD Installation files when you run a Disk Cleanup scan. Microsoft removed the option from Disk Cleanup in later versions of Windows.
Windows ESD Installation files are what let your PC reset itself to factory settings. In general, these files are quite large. That makes them tempting to delete, since you could get back gigabytes of storage. However, the article advises against deleting them. If you run into a serious problem that requires you to reset your PC, you won't be able to.
Windows Upgrade Log Files
These files are less mysterious. Whenever Windows upgrades through updates, a log file is created. These log files can be used to identify and fix problems that occur when your system updates. But if you haven't had any trouble with a recent update, you can safely delete them.
Windows Update Cleanup
Whenever you update Windows, your system keeps older versions of system files on your hard drive. These files let you uninstall updates if you're having problems, so you can roll back to an older, more stable version of Windows. In most cases, you can delete them as long as your PC is running smoothly. However, if you're dealing with persistent problems, you may want to keep them so you can roll back an update and determine whether the upgrade is the source of the issue.
