There's a bump on the back of the head, like a bone bump.

Considering that the occipital bone is touched, the protrusion touched is the occipital eminence, which is a normal physiological structure, but there are certain growth differences, some people will be higher occipital eminence, some will be lower, generally there will be no other symptoms. Pathological conditions are considered to be skull tumor, need to go to the hospital for examination.