Recover Deleted Files with Foremost

Ever deleted an important file? I haven’t recently done this on Linux, but when I used Windows I had a utility for recovering deleted files. Ubuntu Unleashed reported on some data recovery methods on Ubuntu, so I decided to try one of them out.

Foremost is a command line utility for finding and recovering deleted files based on their type. It was origionally developed for the US Air Force Office of Special Investigations.

How is this type of data recovery possible? When you delete a file, the data is not really overwritten.