Humans have senses like sight, hearing, touch, smell, and taste to understand the world around them.
Machines also need “senses” — and they get them through sensors.

A sensor is a device that detects a physical change (like light, heat, or movement) and converts it into an electrical signal that a microcontroller can understand.

For example:

• A light sensor can help streetlights turn on automatically at night.
  
• A gas sensor can detect smoke or dangerous gases in the air.
• A motion sensor can trigger alarms when someone enters a room.