What class dose a script derive from

When I make a java script file in Unity it is obviously a class on its own, but what class dose the script derive form and how would I extend the base javascript class.

Every UnityScript (i.e. Unity’s javascript) script file extends MonoBehaviour. If you want to create a class that extends something else, you need to define the class in a .js file and use the extends keyword.

public class MyChildClass extends MyBaseClass{}

Each script will be its own class.