Adapters for Canon EOS-M cameras (EF-M mount)

The Canon EF-M lens mount, introduced in 2012, is a derivative of the Canon EF lens mount designed for use with the Canon EOS M mirrorless interchangeable-lens camera. Mechanically, it is a bayonet-style mount, and all communication between camera and lens takes place through electrical contacts; there are no mechanical levers or plungers. 

The DSLR EF mount differs from the EF-M mount, you need an adapter to place a EF mount lens on a EF-M mount mirrorless camera. The other way around, using a EF-M mount lens on a EF mount camera makes no sense.

All Canon DSLR Cameras use the EF mount (see EOS EF adapters). All Canon EOS-M cameras use the EF-M mount. (see adapters below). Canon cameras that use the EF-M mount are EOS-M, -M2, -M3, -M5 and -M10.

Information about the Canon EOS system can be found here, information about the EF-M mount can be found here on Wikipedia.