Performing a Disk Cleanup can keep your Windows
Effects of Temporary and Deleted Files
Like most computer users, you likely don't have the time or patience to constantly inspect your hard drive for files that can or should be deleted. But Windows has a knack for accumulating files over time that the operating system no longer requires. For example, when you install software, Windows often places certain files in a temporary location with the intention of deleting those files when you reboot your computer or at another specified time. Occasionally, Windows fails to delete those files, in turn consuming hard drive space and creating conflicts with other system components. Files can also accumulate on your hard drive when you delete them. When you delete files, they are sent to the Recycle Bin, where they remain until you empty it or use Disk Cleanup. Like temporary files, it's easy to overlook the presence of files in the Recycle Bin, and those files can accumulate to massive storage levels over time.
The most immediate benefit of using Disk Cleanup is freeing valuable hard drive storage space. Modern hard drives offer plenty of storage, but this entices users to store massive files, including video and other media-related content. Deleting those files will not free up hard drive space until you empty the Recycle Bin or use Disk Cleanup. Likewise, temporary files (including temporary Internet files) can balloon to sizes in the hundreds of megabytes or more, potentially decreasing Windows' ability to perform efficiently.
With Disk Cleanup, Microsoft created a tool that's simple and fast to use. The interface lets you select the type of files to delete, including temporary Internet files, files in the Recycle Bin, standard temporary files and others. When you select the files you want to delete, Disk Cleanup also shows you the amount of disk space you will gain after the utility deletes the files.
Using Disk Cleanup is not the last word in deleting temporary and other unused files from your system. This utility is unable to determine whether files residing on your Windows Desktop or in your personal folders are useful to you, so it's up to you to occasionally scour your folders to identify potential candidates for deletion. Disk Cleanup also deletes temporary Internet files used only by Internet Explorer. If you use another browser, be sure to use that browser's tools for deleting temporary files.
Before selecting every deletion category in Disk Cleanup, carefully inspect the categories to ensure you're not deleting files you might need.
Delete Restore Points
If you configured the system restore feature to create restore points regularly, you might not realize these are eating plenty of hard drive space. You can use Disk Cleanup to easily remove restore points you no longer need. When using this option, Disk Cleanup will ask if you'd like to delete all but the most recent restore point. If your system runs without problems, this is generally a safe action to take.