This example demonstrates a simple interactive reveal mechanism using plain HTML, CSS, and JavaScript. The page displays a heading that, when clicked, toggles the visibility of a hidden paragraph. The code uses the Document Object Model (DOM) API via `getElementByClassName` and an inline `onclick` event handler to switch between two CSS classes, `reveal` and `revealed`, which control the `display` property of child elements. This minimal approach highlights basic DOM manipulation and event handling without external libraries.