I have been learning JavaScript and Unity for a week now. I learned how to make Cube as a Ground and another Cube as a player and I used this code to make the Player Cube move forward and backward and jumping var walkspeed: float = 5.0; var jumpheight: float = 250.0; var grounded = false; function Update() { rigidbody.freezeRotation = true; if (Input.GetKey("a")) transform.Translate(Vector3(-1, 0, 0) * Time.deltaTime * walkspeed); if (Input.GetKey("d")) transform.Translate(Vector3(1, 0, 0) * Time.deltaTime * walkspeed); if (Input.GetButton("Jump")) { Jump(); } } function OnCollisionEnter(hit: Collision) { grounded = true; } function Jump() { if (grounded == true) { rigidbody.AddForce(Vector3.up * jumpheight); grounded = false; } } I also learned how to make a character hit box. how to make a sprite and animation. pretty much the basic stuff. Couple of days ago I created simple ground in Photoshop and a simple character and imported them to Unity3D. Whenever I use my code above the character keeps falling from the scene. Like the character has nothing to stand on. After thinking about it it make sense because I really didn't make anything to make the player character understand that he should stand on something so I started reading about this issue and I realized that there is something called Collider2D and Rigidbody2D. Now I'm really stuck here I just don't know what to do. I applied the rigibody2d to my character picture and the Collider2D to the ground picture but whenever I play the project the gravity makes my character falls down. This is my question: How can I make the rigibody2d object realize that it shouldn't fall if there is a Collider2D object under it? So when I jump it's going to jump and the gravity going to bring it back to the ground.