Juvenile delinquency, also known as juvenile offending, is the act of participating in unlawful behavior as a minor or individual younger than the statutory age of majority. These acts would otherwise be considered crimes if the individuals committing them were older. The term delinquent usually refers to juvenile delinquency, and is also generalised to refer to a young person who behaves an unacceptable way.

His Majesty's Young Offenders Institution are youth detention centres for offenders between ages 15 to 21 in the United Kingdom. These offenders will have received a custodial sentence following criminal offence convictions or may be being held on remand awaiting trial on pending charges.