Baudrate

Hello all,

what is baud rate and why do we use while we program in Arduino environment? Can anyone Please tell me?

for example:

void setup { Serial.begin(230400); // or 3456000 or 500000 }

This should clear it up: https://en.wikipedia.org/wiki/Baud

Why we use it? Because we most of the time use a Serial interface (to debug).