A judge, or justice, is an official who presides over a court of law. The powers, functions, method of appointment, discipline, and training of judges vary widely across different jurisdictions. The judge is like an umpire in a game and conducts the trial impartially and in an open court. The judge hears all the witnesses and any other evidence presented by the prosecution and the defence. If the accused is convicted, then the judge pronounces the sentence.
There are significant differences between the role of a judge in the common law system descended from British practice, and civil law systems descended from continental European judicial practice. The descriptions below are necessarily archetypical. Details vary from judicial system to judicial system. In many cases, the judicial systems have experienced convergent evolution, expressly or unconsciously adopting similar practices or operating in a manner that minimizes the impact of formal differences between the archetypical role of each system's judges.