PCTuneUp Free Disk Cleaner is just like a sweeper to help you clean up the harddrive. Therefore, you can ensure that you have enough space left over for the system to use for things like application installation, system file storage, and paging. It can scan the whole disk to find out all kinds of junks that has taken up your disk like temporary files, recently used documents, system log, old updates, etc. and let you remove them permanently.