user57005: I cannot find the answer from official document and also surprised no one asked the same question.
What is the default baud rates if I didn't call Serial.begin?

user7508: There is no default baud rate. When the sketch starts, the serial port
is disabled (thus non-functional). Calling Serial.begin() enables the
port.

57005: <p>I cannot find the answer from <a href="https://www.arduino.cc/reference/en/language/functions/communication/serial/begin/" rel="nofollow noreferrer">official document</a> and also surprised no one asked the same question.</p>
<p>What is the default baud rates if I didn't call <code>Serial.begin</code>?</p>
 7508: <p>There is no default baud rate. When the sketch starts, the serial port
is disabled (thus non-functional). Calling <code>Serial.begin()</code> enables the
port.</p>
