A door rose is the decorative ring or plate around the cylinder, the handle or the knob on the face of the door. It covers the hole made in the door leaf and gives a neat finish, but it does not protect the lock.
You can recognise it because it is thin, it is held by pressure or small screws, and it can often be turned or removed by hand. On lever handles, the rose may have the return spring inside it.
The usual mistake is to think that a cylinder rose is an escutcheon. If the cylinder on your front door only has a rose around it, it is exposed to being snapped or pulled out. Protecting it takes a real escutcheon, fixed from the inside. We explain it under escutcheon installation.