What is Serial.begin(9600)?

The video tutorial explains the function and importance of 'serial begin' in Arduino programming. It covers how to establish serial communication between an Arduino board and a computer, primarily using a USB cable. The tutorial also discusses the practical applications of 'serial begin', such as outputting information to a computer screen and ensuring the baud rate matches between devices for successful communication.

Describe a scenario where you would need to use serial begin in an Arduino sketch.

What happens if the baud rates do not match between the Arduino and the receiving device?