An IPP sentence stands for "Imprisonment for Public Protection" and was a form of indeterminate sentence introduced in England and Wales by section 225 of the Criminal Justice Act 2003. It was intended for serious offenders who posed a significant risk of harm to the public but whose offense did not merit a life sentence. The sentence was abolished in 2012 by the Legal Aid, Sentencing and Punishment of Offenders Act 2012.

An IPP sentence was a minimum term that a person must spend in prison, judged to be a just dessert for the crime committed. After completing the minimum term, the offender could apply to the Parole Board for release. However, the Parole Board would only release an offender if it was satisfied that it was no longer necessary for the protection of the public for the offender to be confined. If offenders were given parole, they would be on supervised license for at least 10 years.

Although there was no limit to how long prisoners could be detained under IPPs, and some may never be released, they could be released on review; an IPP sentence was not a sentence of life imprisonment with a whole-life tariff. IPPs have proved difficult to understand and have led to inconsistent sentencing. They have been given to some offenders, while others who have committed similar crimes have served fixed sentences.

In summary, an IPP sentence was a form of indeterminate sentence introduced in England and Wales for serious offenders who posed a significant risk of harm to the public but whose offense did not merit a life sentence. It was abolished in 2012, and after completing the minimum term, the offender could apply to the Parole Board for release. However, the Parole Board would only release an offender if it was satisfied that it was no longer necessary for the protection of the public for the offender to be confined.