Everyone knows you need free hard drive space to save files. But the need for free disk space goes far beyond saving a Word document or an MP3 file.

The hard drive is utilized by the computer for many things, most of which go on behind the scenes.

System Restore
If you have Windows Me or a newer version of Windows, your computer comes equipped with a function called “system restore.” System restore is a great tool.

If you install a program or a new device that causes your computer to go haywire, as long as you have a restore point from before that screwy device or application was installed, you can restore your computer to its earlier state.

Windows periodically sets restore points, and you can manually set them too, but these restore points take up lots of disk space – sometimes up to 5 or 10 percent of the hard drive.

If you have no free space, you can’t use system restore.

Page file
Your computer uses RAM (random access memory) to store programs that it is currently running, such as web browsers, games, and virus scanners.

Programs that are open, but are not currently in use are stored in what Windows calls the “page file” or “swap file.”

The page file is an area on the hard drive set aside to be used as “extra RAM,” so that the actual RAM is not overly taxed and your computer can run as efficiently as possible.

Windows initially sets aside a chunk of the hard drive to use as the page file, so unless you manually limit the size or disable the page file, any files you save on the hard drive will not impact the page file.

However, if you run a lot of programs simultaneously, it is advisable to increase your page file size, and without free hard drive space that won’t be possible.

Running the disk defragmenter

Windows comes with another useful tool, the Disk Defragmenter.

The defragmenter joins fragmented files and reorganizes the hard drive to make the best use of all available space (which helps your PC run faster).

You should run the defragmenter at least once a month, but you need free disk space in order to run it. (Ideally, at least 10 or 15 percent of your hard drive should be empty before running the defragmenter.)

Quarantine
Most anti-virus programs have an option to quarantine infected files.

The suspect files are set aside in a designated area of the hard drive so they won’t be able to further infect your computer, but if you need to get to the file, it’s still around.

Without free hard drive space, there is no room for quarantine. Therefore your anti-virus program may delete an important file it suspects as a virus and there will be no way of retrieving the file, or the anti-virus may not be able to do its job correctly and not do anything for that file because there is not enough space on your hard drive for it to move the file somewhere else.

Temp files
Your computer can pick up and store temporary files when you’re browsing webpages online and even when you’re working on files in programs, such as Microsoft Word.

Over time, these files will slow your computer’s performance down by decreasing disk space. You can use the Windows Disk Cleanup tool to rid your computer of these unneeded files and to help your PC run faster.

There are many more behind the scene activities that go on with your computer, having low hard drive space would limit its functionality and could cause serious system damages if not addressed properly.

It is best to have your computer optimized at least once every three months to get the best performance, and having it last longer.