A militia is a group of citizens who are organized to provide military support, often in times of emergency or crisis. Unlike a professional army, militias are typically made up of volunteers who may not have formal military training. They can be called upon to assist in local defense, disaster response, or other community needs. Militias have existed throughout history and can vary widely in structure and purpose. In the United States, the Second Amendment of the Constitution mentions the right to bear arms and refers to a well-regulated militia as necessary for the security of a free state.