Criminal laws are rules established by the government to define actions that are considered harmful to society. These laws outline what behaviors are illegal and the penalties for those who break them. They aim to maintain public order and protect individuals from harm. When someone violates a criminal law, they may face prosecution in a court of law. Depending on the severity of the crime, penalties can range from fines to imprisonment. The legal system, including judges and juries, plays a crucial role in determining guilt and administering justice under these laws.