What is the meaning of DOM element in the following statements?

Statement #1

You can add multiple classes to a single DOM element.

Statement #2

The -- point is that inheritance in CSS is done not through classes, but through element hierarchies. So to model inherited traits you need to apply them to different levels of elements in the DOM.

Я знаю, что DOM означаетDomain Object Model, Кажется, это синоним API в заявлениях.