What is the purpose of Serial.println() without an argument? I am attempting to control a stepper motor with Sparkfun's Big Easy Driver, and I see the line "Serial.println();" they put in the example code. Why is there no argument and what function does this serve?

//Declare pin functions on Arduino
#define stp 2
#define dir 3
#define MS1 4
#define MS2 5
#define MS3 6
#define EN  7

//Declare variables for functions
char user_input;
int x;
int y;
int state;

void setup() {
  pinMode(stp, OUTPUT);
  pinMode(dir, OUTPUT);
  pinMode(MS1, OUTPUT);
  pinMode(MS2, OUTPUT);
  pinMode(MS3, OUTPUT);
  pinMode(EN, OUTPUT);
  resetBEDPins(); //Set step, direction, microstep and enable pins to default states
  Serial.begin(9600); //Open Serial connection for debugging
  Serial.println("Begin motor control");
  Serial.println();
  //Print function list for user selection
  Serial.println("Enter number for control option:");
  Serial.println("1. Turn at default microstep mode.");
  Serial.println("2. Reverse direction at default microstep mode.");
  Serial.println("3. Turn at 1/16th microstep mode.");
  Serial.println("4. Step forward and reverse directions.");
  Serial.println();
}
To complement jose can u c's answer: the Arduino Serial object uses
CRLF as the end-of-line marker. That's an ASCII CR (carriage return,
or '\r' in C) followed by ASCII LF (line feed, '\n' in C). Thus,



Serial.println();


is equivalent to

Serial.print("\r\n");