When someone is arrested and taken to a police station they will be taken to the custody area. Here you will be interviewed and may be kept in a cell until a decision is taken about how to proceed.
If as a young person you admit the offence, you may be given a reprimand or final warning. If it is your first offence you may be given a reprimand which will be issued here in the charge room. However if you have already received a reprimand, and the offence is not so serious as to require custody, you will be bailed to receive a final warning. This means that you are able to leave the police station under strict conditions and must report to a certain place at a certain time to receive your final warning.
You can be kept in police custody for up to 24 hours. After that a senior police officer (superintendent) can extend that time up to 36 hours. After that time the police need to take the case to a magistrate and they can extend the detention to a maximum of three days.