A Beginner's Arduino Guide/Projects/Sensors
You can make use of sensors to detect events and changes in the real world, and have your Arduino respond to them.
Common sensors include:
- Photosensors - Measures the level of light in an area.
- Microphones - Often used for detecting loud noises. (Most Arduino computers aren't suitable for voice recognition)
- Ultrasonic rangefinders - Bounces inaudable sounds off of objects and listens for their echo to determine distance from objects.