Nail biting—and gnawing the surrounding skin—usually reflects anxiety, ranging from a mild habit to a deep compulsion. Known as onychophagia, it affects all ages, especially youths. It can damage nails, invite infection, and harm teeth. Persistent biting may hurt self-esteem and social life. Help can include cognitive-behavioral therapy, habit-reversal, stress relief tools, bitter polishes, or, when needed, professional mental-health support.