# Using Built-In Objects in ActionScript

ActionScript is an object-oriented programming language. Object-oriented programming uses objects—data structures that group together properties and methods that control the object's behavior or appearance. Properties are attributes that define an object, such as its size, position, color, transparency, and so on. Methods are functions that belong to an object that can set or retrieve properties of the object, or perform other tasks.

ActionScript includes a number of built-in object, including the MovieClip object and others, which are discussed in this chapter. You can also create your own objects, or classes, using object-oriented programming techniques available in ActionScript 2; see Creating classes with ActionScript 2.