efisys.bin

Generic binary file

A .bin file contains binary data with no fixed format. The extension only states that the content is not text. Common uses are firmware images, data blocks for programs, and raw dumps. The program that made the file defines the structure. To identify the content, examine the first bytes of the file.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.