user-1: I want to know what Serial.begin(9600); does and if it is necessary to write it in the code.

user4143: It enables the UART port and sets it to 9600 baud.  Without it you can't use Serial.print etc. 

-1: <p>I want to know what Serial.begin(9600); does and if it is necessary to write it in the code.</p>
 4143: <p>It enables the UART port and sets it to 9600 baud.  Without it you can't use <code>Serial.print</code> etc. </p>
