File created by Multimedia Builder (MMB), a program used to create front-ends for application and game CDs; stores the user interface design as well as the program functions; used for autorun CD interfaces as well as for small games and multimedia playback applications.

MMB projects can be compiled to standalone executables (.EXE files), which may be burned to a CD. Often the application will be accompanied by an Autorun.ini file, which is also burned to the CD and specifies that the application should automatically start when the disc is inserted into the CD drive. Mediachance, the developers of Multimedia Builder, have stopped developing Multimedia Builder and have labeled it as legacy software. NOTE: MBD is often a mistyped file extension, where the user meant to type the .MDB extension. MDB files are Microsoft Access database files.