How do I clean my hard drive?
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.
When deleting files on the latest 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.
Recovering deleted files takes time and specialised software so it's not something most people will bother doing.
You only need to go to the time and expense of cleaning your hard drive if you don't know where your computer will end up.
So if you're selling your computer to someone you don't know, or giving it away to charity, you may want to make sure the hard drive is erased.
Clean, erase, wipe and shred
There are many different words for cleaning your hard drive but whatever you call it, the result is that the information is overwritten.
Searching the internet turns up lots of software for erasing your hard drive. Eraser, KillDisk and Mutilate File Wiper are examples of popular programs.
If you want to find out more about this type of software, you can search Download.com for words like shred, wipe, erase or clean.
These programs work by overwriting your deleted files several times with meaningless data to ensure that they are completely erased.
Even then, it may still be possible to retrieve the original data, but only by very dedicated experts with extremely powerful recovery software.
A clean start
Another way to make sure the hard drive is wiped is to reformat it and re-install your operating system.
This is a technical operation, so you should only try it if you are confident about what you are doing, or you know someone who is!
If you want to find about reformatting your hard drive, there are step by step instructions on the net inspectors website.
A messy end
If you are still worried that the information on your computer may fall into the wrong hands, you can destroy your hard drive.
You can take the hard drive out of your computer and either burn it, or drill holes in it so no-one else will be able to use it.
However, this is an extreme solution, and it's a shame to destroy your hard drive when a charity would gladly accept it as a donation.