A PTC thermistor, or Positive Temperature Coefficient thermistor, is a type of resistor whose resistance increases with an increase in temperature. These devices are commonly used in temperature sensing and circuit protection applications. When the temperature rises beyond a certain point, the resistance of the PTC thermistor increases significantly, which can help prevent overheating in electrical circuits. PTC thermistors are often found in devices like overcurrent protection circuits and temperature sensors. They are made from ceramic materials and are known for their reliability and quick response to temperature changes. Their unique properties make them essential components in various electronic applications.