Deleted 'stuff'?

[Grandpappy]

If I delete something, eg. a picture,a document,a program,anything and it goes into my wastebin and I then empty my wastebin,it's gone,right? How come I can then use a program like 'Recuva'and get most(sometimes?)of it back? If that 'stuff' is just lying somewhere,then it's taking up space! How can I get rid of it 'permanently and why is it not deleted properly the first time?
Please, any answers or explanations in 'dummy' language. Many thanks

[The Builder]

Deletions aren't removed Grandpap. They are simply "marked" as no longer needed.
That means the space is available to the system again. They are overwritten.

To remove permanently would involve actual physical removal of the data by de-magnetising.

[VHG]

When you have a file on your computer it is held on your hard disk.

To keep track of WHAT files are on your hard disk, and WHERE they are, your hard disk also contains a "look up" table, to point to where the file is.

When you delete a file all Windows does is delete the entry from the look up table (in fact it just marks the file as deleted in the look up table).

The FILE ITSELF is not deleted, but the space where the file is stored is marked that is CAN be overwritten if need be.

So if your hard disk NEVER fills up the "deleted" file could sit on your hard disk for months or years.

But if your hard disk DOES fill up, then eventually the space where your deleted file is will be used by a new file and your deleted file will finally be deleted.

This is why you should NEVER give a PC or hard disk away until you have done a complete CLEAN of the disk, to remove all hidden files.

There is software available to "wipe" all hidden files off the hard disk.

[VHG]

I believe that organizations like the FBI and others can even recover files that to all intents and purposes have been deleted off the hard disk.

Not sure how they do it, but somehow they can recover long deleted files.

Some organizations (like Which magazine, security companies etc) have done tests by buying old computers and hard disk from ebay and other places and have managed to recover all sorts of information such as patient lists from hospitals, bank logon details and so on.

This is why the only REAL way to dispose of a hard disk with sensitive information on it is to smash it up with a hammer.

[bazwillrun]

sorry VHG smashing with a hammer wont work

if theres pieces with recoverable data on then that may be all thats needed to convict/incriminate etc someone or whatever the data is needed for

only real way is to remove the platter and grind it to dust and then dissolve the particles in acid to be doubly sure