For a police officer to investigate whether you have committed a crime, they must first arrest and interview you. Then, if there is enough evidence that you may have committed a crime, you might be charged. That means being brought to court where it will be decided if they find you innocent or guilty.
In some cases, the police might give you a caution instead of charging you. A caution is a strong warning that you could have been sent to court, and almost certainly will be if you commit further offences. The police can only use a caution if you agree to accept it. By consenting, you are in effect agreeing that you are guilty of the offence and once you have consented, you cannot then argue that you were innocent. If you’re arrested and interviewed, the police should always offer to get you a free solicitor. You should always have a solicitor present when the police interview you and take their advice about the implications of accepting a caution, even if you’re told that the matter will be cleared up more quickly if you take it.
A caution is not a criminal conviction (being found guilty in court), but it will be recorded on your criminal record (held on the police national computer). It can be used in court as evidence of bad character if you go to court for something else and your photograph, ﬁnger prints and DNA might still be kept by the police.