A quick format is a process that deletes the files and folders on a hard drive, but does not scan the drive for bad sectors. It is much faster than a full format and is generally used when reinstalling an operating system. A full format, on the other hand, scans the drive for bad sectors, then erases the entire contents of the drive, including any hidden files. It is a much more thorough process and should be used when setting up a new drive or if you suspect there are bad sectors on the drive.