#include <Servo.h>

// Define the analog pin for the potentiometer
const int potentiometer = A0;

// create servo object to control a servo
Servo myServo;  

void setup() {
  // attaches the servo on pin 9 to the servo object
   myServo.attach(9);  
}

void loop() 
{

  // reads the value of the potentiometer (value between 0 and 1023)
  int analogValue = analogRead(potentiometer);  

  // scales it to use it with the servo (value between 0 and 180)
  int angle = map(analogValue, 0, 1023, 0, 180); 

  // sets the servo position according to the scaled value
 myServo.write(angle);

  // waits for the servo to reach the position
  delay(100);  
}