Wiping, unlike normal file deletion in the operating system, overwrites the area on the hard drive or device where the data was stored, making it impossible to recover it.
There are several processes (tech savvy users call them algorithms) that process the data, from overwriting the data with 0s to military grade algorithms that overwrite the data up to 30 times.
There is no real benefit in using advanced methods of wiping files as it has been tested time and time again that data is not recoverable by normal means after being overwritten with 0s.
The efficiency of the deletion can easily be judged by running a file recovery software like Recuva on the device to see if the data can be recovered.
Disk Wiping Software
Devices like digital cameras, external hard drives or cell phones can usually be connected to a computer. Specialized programs can then be run on the computer to erase the data completely. One such tool is Eraser, a free program that erases data. It is available for the Windows operating system and can be used to permanently delete the data on the drive (with the exception of the main Windows drive).
An alternative to Eraser is Darik's Boot and Nuke. It needs to be burned to CD and run during system boot. Windows is not loaded at all which makes it possible to delete the system partition with Windows as well.
There are other free tools available on the Internet that can be used to delete data on devices permanently but those two are more than sufficient for most tasks.
It is highly recommended that you delete the data securely and permanently before selling or giving away devices with storage capacities. After all, we do not want to risk seeing private data leaked on the Internet.
Using Eraser to Delete Data Securely
Eraser is an open source program for the Windows operating system that can be used to make it impossible to recover deleted data on hard drives and external storage devices. The program is very easy to use and suitable for users of all experience levels.
Start the application after installation. Each Eraser task needs to be scheduled in the program. To create a new task click on the New Task link or press Ctrl N.