The element can also be used for typographical effects like pull quotes or sidebars, for advertising, for groups of nav elements, and for other content that is considered separate from the main content of the page. etc. It was originally used in Firefox OS to implement browser applications before that project was cancelled; since Firefox 47 it is available to desktop chrome code and used in places like the Firefox devtools. Such as an advertising sidebar with relevant ads or menu systems with links that lead to related information. It did notappear to be an appropriate element for holding secondary content related to the site as a whole, typically known as a “sidebar”. The HTML