void setup() {
  Serial.begin(9600);  // start USB serial communication at 9600 baud (bits per second)
}

int counter = 0;  // so we have something to print

void loop() {
  Serial.print("Hello, world ");  // send a string
  Serial.print(counter);          // send an integer
  Serial.println();               // send a newline
  counter += 1;                   // counters should count
  delay(100);                     // don't send too fast
}