E4M is an on-the-fly disk encryption product. What this means is create a volume on your hard disk, CDROM, floppy or other media which is essentially just a normal file. The file however is in fact a file system itself. It contains all the structures needed by your operating system to recognise the file as a file system of a particular type such as FAT or NTFS. This is called a "file hosted volume". Or you could choose a blank or unwanted partition on a local hard disk or floppy disks and format it using E4M. You can then mount this new encrypted volume, and use it like you would any other drive. This is called a "Raw partition volume". To your operating system, these new volumes will work exactly like your C drive, or any other drive on your system.