In the past ten years, the electronic memory and its storage capacity has undergone earth-shaking changes. To the different types of disc storage capacity is only 1.44MB floppy, and then to tape, hard disk, magnetic memory, electronic memory storage capacity is growing smaller and smaller, the prices are getting lower and lower. It is because of these reasons, these electronic memory applications on the market more and more widespread, and even has completely changed the way people handled the documents and information. The hard disk is now very widely used storage tool. Printers, copiers and other office equipment, there is also the use of the hard disk.

        Special storage principle due to the hard disk, even after formatting, broken even after combustion, on which the contents of the still be able to be restored. Therefore, if no special destruction is likely to cause a very serious leak.