b element Displays the text of the element as boldface text, hgroup element The HTML Headings Group Element (<hgroup>) represents the heading of a section, iframe element Defines an inline frame (ie a frame embedded in a document). 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':