Adapters for Canon EOS cameras (EF mount)
Introduced in 1987, the EF lens mount is the standard lens mount on the Canon EOS family of SLR film and DSLR digital cameras. 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 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 below). All Canon EOS-M cameras use the EF-M mount. (see EOS EF-M adapters)