How does 'Instantiate' convert easily between GameObject and Component?

Code (CSharp):

1. public class Missile : MonoBehaviour
2. {
3.     public int timeoutDestructor;
4.  
5.     // ...other code...
6. }
7.  
8.  
9. public class ExampleClass : MonoBehaviour
10. {
11.     // Instantiate a Prefab with an attached Missile script
12.     public Missile projectile;
13.  
14.     void Update()
15.     {
16.    
17.         if (Input.GetButtonDown("Fire1"))
18.         {
19.             // Instantiate the projectile at the position and rotation of this transform
20.             Missile clone = Instantiate(projectile, transform.position, transform.rotation);
21.  
22.  
23.         }
24.     }
25. }

This is from the docs. I always took it for granted, but got curious how this method knows how to return a specific component, but also an object. I can see that it uses generics ( public static T Instantiate<T>(T original) where T : Object; ), but how does a component fall under object? When I try to write this myself, I get an error.

Anyhow, just thought I'd ask, maybe I and others can learn something useful here?

 

Capitalization matters:

object

is not

Object

... in this case

Object

means

UnityEngine.Object

and the reason it works is: