In HTML5, browser makers must continue to support certain crusty legacy elements. Web developers though should quit using them. For example, most of us have stopped using and should continue avoiding the
tt elements in HTML5. CSS is the way to go here. To no one’s surprise, the HTML5 no-fly-zone includes the
noframes elements because of their history of aggression against usability and accessibility.
For more information on elements to avoid, see “Absent Elements” on the W3C site.