The DOM (Document Object Model) is the data representation of the objects that make the structure of
a document on the web. JavaScript uses the DOM to access the document and its elements.
Who is responsible for DOM specifications?
Up until 2018, the WC3 was responsible for all specifiations. However, now broswer vendors are responsible.
DOM implementation in browsers.
Basically, the DOM takes the items defined in the code and arranges them in a way that the browser understands.