What is Arduino in simple words?

Related questions

1. Does Arduino have an operating system?
2. Which Arduino board is best for beginners?
3. Which programming language is best for Arduino?
4. Can you run Linux on Arduino?
5. What is Arduino sketchbook?
6. What is Arduino good for?
7. Where is Arduino installed?
8. Does Arduino have to be connected to a computer?
9. Which is easier Raspberry Pi or Arduino?
10. What file extension is used when saving sketches written with the Arduino IDE?

Tags

1. #platform
2. #light
3. #button
4. #source
5. #output
6. #inputs
7. #online
8. #based
9. #finger
10. #activating
11. #turning
12. #arduino
13. #twitter
14. #message
15. #hardware
16. #software
17. #boards
18. #something
19. #electronics
20. #publishing
21. #sensor
22. #motor