PIR sensors allow you to sense motion, almost always used to detect whether a human has moved in or out of the sensors range. They are small, inexpensive, low-power, easy to use and don't wear out. For that reason they are commonly found in appliances and gadgets used in homes or businesses. They are often referred to as PIR, "Passive Infrared", "Pyroelectric", or "IR motion" sensors.
This PIR (Motion) Sensor can detect the infrared signals from human body or other animals and triggers with movement. So it can be applied to a variety of scenarios which require motion detection. Conventional pyroelectric infrared sensors require body pyroelectric infrared detector, integrated chipsets, complex peripheral circuit. So the size is slightly big, circuit is complex, and reliability is slightly lower. We bring this new pyroelectric infrared motion sensor which is specially designed for your Arduino projects, an integrated digital body pyroelectric and infrared sensor, with small size, high reliability, low power consumption, and simple peripheral circuit. Very simple to use in any project.