Our computers and mobile phones contain all manner of personal data, from documents featuring details of your date of birth and address to financial records and family photos.
Yet every year thousands of hard drives end up undeleted on the scrap heap or, worse, sold on to third parties who may be able to access those details.
The risks of personal information falling into the wrong hands include identity theft or people gaining access to sensitive information they could use to access your online accounts.
But taking control of your data when it's time to upgrade to a new machine or device is actually simple. Follow these steps and your old bits won't resurface and come back to bite you.
Deleted files can be recovered
Simply deleting a file from your hard drive doesn't mean it's no longer there – it just means the computer doesn't know where to go and look for it.
A forensic expert, digital criminal or any ne’er-do-well with the right equipment could easily access every single detail even from deleted hard drives that look empty to the untrained eye.
Even if you're only passing an old laptop on to a relative, it's still worth taking precautions, in case they don't wipe the machine when they upgrade.
Data-wiping programs
In order to really eradicate data you need to use software tools that will overwrite the data physically on your hard disk.
The programs overwrite the data that was there before, often up to seven times, making it almost impossible for anyone to retrieve it later. They're the sort of thing used by government departments in a bid to prevent data leaks.
In tests, we found the free Disk Doctors Data Sanitizer easy to use and effective at permanently destroying data. There’s a paid-for version that uses more complex data-overwriting techniques.
Donate your old PC to charity
Charities like Computer Aid will accept machines that aren't too long in the tooth and clean all the information from the machine for you.
Manually destroying your hard drive
It might not be the most environmentally friendly option, but taking a hammer to a hard drive can be a therapeutic and effective way of destroying data.
Of course, it means you can't sell or pass it on to anyone else, but you know the data is destroyed for good.