Understanding the Question:
Drug and alcohol abuse is the habitual, harmful use of substances, and prevention means the steps taken to stop it from starting or spreading.
Detailed Explanation:
Avoiding peer pressure and choosing friends carefully protects young people from the initial exposure that often leads to abuse.
Open conversation between children and parents builds trust, so warning signs can be caught early rather than hidden.
Education about the dangerous effects of drugs and alcohol, delivered at school and through the media, helps people make informed choices.
If abuse has already started, professional medical and psychological counselling is needed, and appropriate help should be sought from a qualified doctor rather than self-treatment.
Final Answer:
Prevention relies on avoiding peer pressure, open family communication and education, while control of existing abuse needs proper medical and psychological help.