Convenience of a hands-free faucet available at home, too

There are two main categories of technology used to make a faucet touchless. One uses an infrared sensor that projects an invisible beam of light. When you put your hand in front of that beam, your hand reflects the light back to the sensor, which then signals to the faucet to release the flow of water.

https://www.macfaucets.com/index.php?route=mblog/article&article_id=4