Cast a ray from a camera

The most common use of a Ray from the cameraA component which creates an image of a particular viewpoint in your scene. The output is either drawn to the screen or captured as a texture. More info
See in Glossary is to perform a raycast out into the sceneA Scene contains the environments and menus of your game. Think of each unique Scene file as a unique level. In each Scene, you place your environments, obstacles, and decorations, essentially designing and building your game in pieces. More info
See in Glossary. A raycast sends an imaginary “laser beam” along the ray from its origin until it hits a colliderAn invisible shape that is used to handle physical collisions for an object. A collider doesn’t need to be exactly the same shape as the object’s mesh - a rough approximation is often more efficient and indistinguishable in gameplay. More info
See in Glossary in the scene. Information is then returned about the object and the point that was hit in a RaycastHit object. This is a very useful way to locate an object based on its onscreen image. For example, the object at the mouse position can be determined with the following code:

using UnityEngine;
using System.Collections;

public class ExampleScript : MonoBehaviour {
    public Camera camera;

    void Start(){
        RaycastHit hit;
        Ray ray = camera.ScreenPointToRay(Input.mousePosition);
        
        if (Physics.Raycast(ray, out hit)) {
            Transform objectHit = hit.transform;
            
            // Do something with the object that was hit by the raycast.
        }
    }
}