A Borstal was a type of youth detention centre in the United Kingdom, several member states of the Commonwealth and the Republic of Ireland. In India, such a detention centre is known as a Borstal school.

Borstals were run by HM Prison Service and were intended to reform young offenders. The word is sometimes used loosely to apply to other kinds of youth institutions and reformatories, such as approved schools and youth detention centres. The court sentence was officially called "Borstal training". Borstals were originally for offenders under 21, but in the 1930s the maximum age was increased to 23. The Criminal Justice Act 1982 abolished the Borstal system in the UK, replacing Borstals with youth custody centres.

In India, Borstal schools are used for the imprisonment of minors. As of 31 December 2014, there were twenty functioning Borstal schools in India, with a combined total capacity of 2,108 inmates.