header element The HTML Header Element (<header>) represents a group of introductory or navigational aids, sub element Specifies that the enclosed text should be rendered in the browser as subscript, command element The command element represents a command which the user can invoke. These elements allows child elements from interactive, embedded, heading, sectioning, phrasing, and metadata content categories.
Click the html element name in the punctuation list to advance the example in 'Tryit-Editor':