5 Myths and half truths about computers and the internet

When you install something to your hard drive it’s there permanently. –PARTIALLY TRUE.

The Myth:
We’ve all heard the horror story. You’re mate’s dad’s nephew threw away his old computer, and three days later his credit card information had been stolen! There was this company right, and they threw away old PC’s and hackers nicked the computers and got loads of personal information they sold to spammers!

Cases like this DO happen, but this doesn’t mean they’re common. With a little effort, you can ensure no data at all survives on your old hard drive. In order to understand this half truth, and how you can make sure this doesn’t happen to you, we need to look at how a hard drive works.
The Facts:

Imagine your hard drive is a giant library. Every library has a reception desk, in the case of the hard drive, we call this the index file. Now when you run a program, your computer needs to get the program from your hard drive. So it goes to the index file and asks where all the information on the hard drive is.

Just like when you go to the library and ask where a book is.

When you delete something from your hard drive, it isn’t actually removing the data, it’s only removing it’s entry from the index file. So as far as your computer is concerned, that data no longer exists, even though it is physically still there. That’s where the myth comes from!

But, when you put information on your hard drive (Say installing a new game), the index file looks for gaps in the bookshelf to put the new program. Remember, as far as the computer is concerned, a file that isn’t listed in the index does not exist, so if it finds that the spot on the hard drive previously occupied by the removed file is big enough for the new program, it will write over the old file with the new one.

Hard drives store data using magnetism, so the new magnetic pattern destroys the old one. Without getting too technical, bits of the old program may survive, and can be rebuilt by specialist programs.
Safeguards:

There are many programs that will fill up your hard drive with ‘junk data’ overriding everything on the drive, then they’ll do it again and again and again until all that’s present on the drive is a junk string of 0’s and 1’s. Many of these are available free online.

There’s also a low tech solution too. It’s called a hammer.

Read the article in it's entirety here.