PTC thermistors, or Positive Temperature Coefficient thermistors, are temperature-sensitive resistors that increase their resistance as temperature rises. They are commonly made from ceramic materials and are used in various applications, including overcurrent protection and temperature sensing. When the temperature exceeds a certain threshold, a PTC thermistor can limit the current flow in a circuit, preventing damage to electronic components. This property makes them valuable in devices like power supplies and motor controllers, where maintaining safe operating conditions is crucial.