Underage drinking is common among those aged 12 to 25 and can have negative impacts on physical and mental health as well as education and family life. Warning signs of underage drinking include behavioral or academic problems, changes in friends, and signs of intoxication. Risk factors include genetics, mental health issues, and social influences. Underage drinking is linked to car accidents, assaults, unsafe sex, and alcohol poisoning. Prevention strategies target schools, families, and policies to reduce availability and promote awareness of risks.