A birthmark is a colored mark on or under the skin. There are many kinds of birthmarks, including salmon patches, café-au-lait spots, hemangiomas, and more. They can be any size or shape and can be different colors. Some birthmarks are smooth, and some are raised. Nearly all birthmarks are harmless and painless. But it’s important to have a doctor check all birthmarks, just to be sure they are okay. Follow the links below to find WebMD's comprehensive coverage about birthmarks, what they look like, how to treat them, and much more.