You can clean your hard drive by deleting files you no longer need, and to make sure the hard drive is erased, you can 'wipe' it with special software.

This is good because there may be sensitive data on your hard drive, such as your bank account details, that you do not want other people to see.

For example, if you are selling your old computer to someone you don't know, you may want to make sure the hard drive is cleaned first.

Gone but not forgotten

When you delete a file on your computer it is not really deleted, it actually just gets hidden.

The information is still there until it gets overwritten, which only happens when your hard drive is full and your computer needs to find more space.

If you don't store a lot of large files like graphics, music or video, your hard drive will never fill up and your computer won't need to overwrite the files you have deleted.

Hard disk space

When deleting files on Macs, you can overwrite them by selecting 'Secure Erase Trash' from the 'File' menu in the finder.

For other computers you need special software to overwrite deleted files, but first ask yourself if it's really necessary.

Your computer's new home

If you're giving your computer to a trusted friend or someone in your family, then you probably don't need to worry about cleaning your hard drive completely.