This element was never added to the HTML specification and support for it varied widely across browsers. People often had very strong opinions about the use of this element — both positive and negative. But whether you loved or hated it, it did serve a purpose of making content that overflowed the box boundaries visible. Now we can use it “legally” with the power of CSS, look at the demo:

 

See the Pen Marquee is alive with CSS3 by Avaz Bokiev (@samarkandiy) on CodePen.