How do I make my player stop moving when I release the button that I am pressing?

I'm writing a script in which my player moves from left to right using the right/left arrow keys. My problem is that my character will not stop moving once I let go of the arrow. I am new to coding so Can you please explain simply. Here is my script (C#): using UnityEngine; using System.Collections; using System;

public class mover : MonoBehaviour { public float moveSpeed; private float position = 0;

 // Use this for initialization
 void Start()
 {
     
 }
   
 // Update is called once per frame
 void Update()
 {
     if (Input.GetKey(KeyCode.RightArrow))
     {
         GetComponent<Rigidbody2D>().velocity = new Vector2(+moveSpeed, GetComponent<Rigidbody2D>().velocity.y);
     }
     if (Input.GetKey(KeyCode.LeftArrow))
     {
         GetComponent<Rigidbody2D>().velocity = new Vector2(-moveSpeed, GetComponent<Rigidbody2D>().velocity.y);
     } 



 }

   
 }