Any “markup language” has two basic components: the content, and the markup. Semantic HTML. In HTML there are some semantic elements that can be used to define different parts of a web page: Certain elements support this capability. the section on elements in the Introduction to HTML article, Assessment: Structuring a page of content, From object to iframe — other embedding technologies. When a screen reader, or any sort of assistive device scans a web page, it gets information about the Document Object Model (DOM), or the HTML structure of the page. Elements such as