A heart valve is a structure in the heart that regulates blood flow between its chambers. There are four main valves: the mitral valve, tricuspid valve, aortic valve, and pulmonary valve. Each valve opens and closes at specific times during the heartbeat, ensuring that blood moves in the correct direction and preventing backflow. Heart valves are made of flexible tissue and are essential for maintaining efficient circulation. When valves do not function properly, it can lead to conditions such as valvular heart disease, which may require medical intervention, including surgery or medication to restore normal function.