The E01 file extension stands for EnCase image file format used by EnCase software. The file is used to store digital evidence including volume images, disk image, memory and logical files. Encase creates multiple E01 files of uniform size 640 MB for storing the acquired digital data.
One of the most distinct features of this file format is that for every new E01 file, the extension of the file changes for every new file that is created. Since EnCase was originally introduced with the name Expert Witness, E01 file may often be referred as, Expert Witness files.