DOM
The Document Object Model, or DOM, is the browser’s object representation of a document such as an HTML page.
Scripts can read and modify DOM nodes, attributes and text. The DOM is distinct from the HTML source: it is the parsed document tree exposed to programming interfaces.
The browser’s live document tree
Scripts can read and modify DOM nodes, attributes and text. The DOM is distinct from the HTML source: it is the parsed document tree exposed to programming interfaces. In practical terms, DOM belongs to the browser, server or document layer. Knowing that layer is important because it tells you what the term can change, what it cannot change, and where to look when something behaves unexpectedly.
Selecting and changing a node
When JavaScript runs document.querySelector(".menu"), it is selecting a node from the DOM created after the browser parses the HTML.
Where the DOM differs from page source
You do not need to memorize the term in isolation. It becomes useful when you can recognize it in the tool, browser, file or conversation where the concept is doing real work.
DOM is not another word for HTML
The Document Object Model, or DOM, is the browser’s object representation of a document such as an HTML page. By contrast, HTML, or HyperText Markup Language, is the markup language used to define the structure and meaning of content in a web document. The two can appear in the same project, but they describe different parts of the work and should not be used as interchangeable labels.
The mistake: debugging source instead of live state
The common mistake is to use DOM as if it also meant HTML. That blurs two separate decisions and usually sends troubleshooting in the wrong direction. A better test is practical: Open the Elements panel: the live DOM may differ from the original page source after scripts modify it.
Why the live tree matters to scripts
In day-to-day work, DOM matters when scripts read or change the live document tree. The practical value is not the vocabulary itself; it is being able to identify the right control, file, setting or decision when the concept becomes relevant.
When JavaScript runs document.querySelector(".menu"), it is selecting a node from the DOM created after the browser parses the HTML. That example is useful because it turns the definition into something you can recognize, test and discuss with other people working on the same project.
Related terms worth learning next
Sources and further reading
Use these references when you need documentation-level detail, specifications or product-specific behavior beyond the plain-English explanation above.