What are those black spots on skin called?

See doctor. to have black spots evaluated to make sure they are not cancerous moles.
Eval. This can't be diagnosed with the information that is available. A history, physical examination & other studies may be needed to determine cause/causes. Once accurately assessed a treatment plan can be developed.
Difficult to answer. Unfortunately "black spots" is not specific enough for me to give you a good answer. If you could describe what you mean then perhaps we could give you a better answer.