When you build web pages, you often want them to do more than just display static information. You might want your page to access the user's location, let users drag and drop files, or even copy text directly to their clipboard. This is where APIs come in. An API—which stands for "Application Programming Interface"—is a set of tools and rules that lets your web page interact with features provided by the browser or device.

APIs are built into modern browsers and are designed to enhance your web pages with new capabilities. They allow you to do things like:

• Access device hardware, such as the camera or microphone;
• Store data locally in the browser for offline access;
• Enable drag-and-drop functionality for files or elements;
• Read from and write to the user's clipboard;
• Request the user's geolocation to show relevant content.

These APIs are not part of the HTML language itself, but rather, they work alongside HTML, CSS, and JavaScript to make your web pages interactive and powerful. By using these APIs, you can create richer and more engaging experiences for your users, all within the browser—no extra plugins or downloads required.

To see how you might get started with APIs, here is a simple HTML page structure. In later chapters, you will learn how to add API features to this page to make it interactive and dynamic.