Prison is a place where people who have done bad things go to stay. The people who go to prison are called prisoners. Prisoners will have to stay in prison for a certain amount of time, and they are not allowed to leave until their time is up. The time a prisoner has to stay in prison is usually decided by a court or judge. In some cases, the prisoner may even have to stay in prison for the rest of their life. Prison can also be used as a punishment for people who commit crimes.