Lots of information like ping sonar sensor, distance, and ping sensor are explained in the datasheet. The datasheet gives us info such as ultrasonic, the ping sensor, and measurement.
Inside the datasheet we can read explanation regarding microcontroller, ultrasonic distance sensor, and sonar sensor. Below are some excerpt from the datasheet:
The Parallax PING))) ultrasonic distance sensor provides precise, non-contact distance measurements from about 2 cm (0.8 inches) to 3 meters (3.3 yards). It is very easy to connect to BASIC Stamp® or Javelin Stamp microcontrollers, requiring only one I/O pin. The PING))) sensor works by transmitting an ultrasonic (well above human hearing range) burst and providing an output pulse that corresponds to the time required for the burst echo to return to the sensor.
Even more, the datasheet explains discussion such as distance sensor, and conversion.