"Common warts (verruca vulgaris) - these have a rough surface. They are firm and raised and may have a cauliflower surface type look. They are thickened bumps called papules or plaques. Common warts may appear in any part of the body, but are more common on the knuckles, fingers, elbows and knees. Often they have tiny dark spots which are from blood vessels that have clotted."
Looks like a wart or corn. I had a couple on my fingers in my early 20s and got rid of them by using some wart remover gel for a couple of weeks.
This is a wart and the black dots inside of the ring are the roots, which go down deeper into your skin.
You can buy over the counter wart remover for it and follow the instructions carefully.
Or, you can go to your doctor who will freeze it off. Sometimes with this and also with the over the counter meds, you may need more than one application.
Warts are contagious, so it is likely that you touched someone who had a wart.