A skin tag is soft and skin colored or dark, and is a small lump or "stretch" that hangs out from the skin. Size is from 1 mm to 5 cm. It consists of skin with blood vessels and some connective tissue. They are most common on the neck and in skin folds such as the armpits and groin. They are more frequent in people who are overweight. Usually causes no other problem than the cosmetic one.
The cause is unknown, but they come with age. Skin friction and hormonal conditions may play a role.
These can be removed with the help of freezing, cutting or burned away by a doctor. They can also be "choked" by tying a tight thread around the skin tag.