Sunspots are little areas of hyperpigmentation that are generally harmless (although they can be unsightly). They’re caused by years of sun exposure, which triggers pigment-producing cells called melanocytes in your skin to produce more pigment in a small concentrated area.
This excess pigment is triggered in response to injury (sun damage), sort of in the same way scar tissue forms after a cut or puncture wound. Unlike moles that tend to‘stick out’ above the skin, sunspots aren’t raised at all — run your finger over a sunspot and it will feel just as smooth as the skin around it.
But just because sunspots are considered harmless doesn’t mean they should be ignored. The problem with sunspots (and moles, for that matter) is that skin cancer in its earlier stages can also look very much like a flat, brownish spot (as you can see in the image below). This means that if you ignore an area of hyperpigmentation on your skin, you could be delaying treatment for what may turn out to be melanoma.