The Document Object Model, or DOM, is a tree-like structure that browsers create to represent every element, attribute, and piece of text in an HTML page. Each element in your HTML—such as headings, paragraphs, images, and links—becomes a node in this tree. This structure allows JavaScript to access, modify, and interact with the content and layout of a web page dynamically. When you load a web page, the browser builds this DOM based on the HTML source, making every part of the page available to JavaScript code for manipulation.