A mistrial occurs when a trial cannot proceed to a verdict due to a significant error or issue that affects the fairness of the proceedings. This can happen for various reasons, such as juror misconduct, improper evidence being presented, or a hung jury, where jurors cannot reach a unanimous decision. When a mistrial is declared, the case may be retried later. In the legal system, a mistrial is important because it protects the rights of the accused and ensures that justice is served. If a mistrial is declared, the prosecution may choose to retry the case, or the defendant may be acquitted, depending on the circumstances surrounding the mistrial.