Whats the use case of proximity sensor? Can anyone explain to me what is the purpose of the proximity sensor, on my phone. What if my phone's proximity sensor stops working or gets damaged. What problems will I face?

PS: I am just curious to know.
The proximity sensor on most smart-phones with touchscreen exists to disable accidental touch events. The most common scenario is the ear coming in contact with the screen and generating touch events, while on a call.