1. HTML4 Tutorial
2. The Web
3. HTML and URLs
4. HTML Element Structure
5. HTML Document Structure
6. HTML - Create Your First HTML Document
7. HTML Text Formatting Elements
8. HTML Entities
9. HTML Lists
10. HTML Links
11. HTML and Images
12. HTML Tables
13. HTML Forms
14. HTML div and span Elements
15. HTML iframe
16. HTML Meta Tags
17. CSS Introduction
18. JavaScript Introduction
19. XHTML Introduction

JavaScript makes it possible to make your HTML document dynamic, meaning you can change the HTML document while it is being displayed in the browser.

JavaScript is a programming language. You embed JavaScript code inside your HTML using the script element, like this;

<script>
    alert("This is a JavaScript code snippet");
</script>    

This little example shows a JavaScript alert box with the text This is a JavaScript code snippet.

The JavaScript code is executed when the browser encounters it in the browser. That may actually be before the full HTML document is loaded.

You can do a lot with JavaScript. For instance, you can:

• Listen for events on form elements.
• Listen for events on HTML elements in general (on mouse over, mouse out, click etc.)
• Execute scripts at timed intervals.
• Change the HTML document.
• Change the CSS styles used by HTML elements.
• ... and much, much more...

JavaScript is a big topic to cover, so this tutorial will not get into more detail about JavaScript. The internet is full of JavaScript tutorials, so a quick search on the web will reveal a lot of resources that can help you learn JavaScript.