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Trail: Getting Started
Lesson: The Anatomy of an Applet

## Defining an Applet Subclass

> The first bold line of the following listing begins a block that defines the `HelloWorld` class.

> >     import java.applet.Applet;
> >     import java.awt.Graphics;

> >     public class HelloWorld extends Applet {
> >         public void paint(Graphics g) {
> >             g.drawString("Hello world!", 50, 25);
> >         }
> >     }

> The `extends` keyword indicates that HelloWorld is a subclass of the class whose name follows: `Applet`. If the term subclass means nothing to you, you'll learn about it soon in Object-Oriented Programming Concepts.

> From the `Applet` class, applets inherit a great deal of functionality. Perhaps most important is the ability to respond to browser requests. For example, when a Java-capable browser loads a page containing an applet, the browser sends a request to the applet, telling the applet to initialize itself and start executing. You'll learn more about what the Applet class provides in the Overview of Applets lesson.

> An applet isn't restricted to defining just one class. Besides the necessary `Applet` subclass, an applet can define additional custom classes. When the applet attempts to use a class, the application that's executing the applet first looks on the local host for the class. If the class isn't available locally, it's loaded from the location that the `Applet` subclass originated from.

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