When you delete a file from Windows it just mark the file as deleted in file allocation table, but the data of the file is still on your hard disk, Windows does not physically remove deleted files from your hard disk.
Emptying your Recycle Bin does NOT protect you at all.
Your sensitive files can be recovered, even after you format your hard disk! This powerful program helps you shred important files & folders so that they cannot be restored & prevent attempts to recover sensitive deleted files from your hard drive by data recovery or forensic 软件. Shredder allows you to purge, wipe & erase data with methods that far exceed US Department of Defence standards for file deletion (DOD 5220.22). Easily automate the cleaning process with batch files, scheduler and shortcuts. Completely remove sensitive data from your hard drive by overwriting it several times with carefully selected patterns. Overwrites all bits in selected files, including cluster slack space, with binary 1's, 0's, and/or random bit patterns. Supports complete folder deletions including subfolders. Shreds disk free space so you can even use shredder to destroy previously deleted files on your hard drive. Drag & Drop files or entire folders Delete even if the file is locked! No trails are left of any compromising or confidential information. Easily choose the number of overwrites according to your 安全 ambitions. The higher the number the less the probability that even finest magnetic tracks could be detected. The Department of Defense (DOD 5220.22-M) recommends seven passes for top 安全. You can also shred files by right-clicking on them from the MS Windows Explorer or on the recycle selecting and bin the shred item on the popup context menu.