User blog comment:Brandon Rhea/Making Ads Better: The Basics/@comment-80.229.116.230-20170117222806/@comment-1524681-20170117234656

It's like looking at a newspaper article, and one of the ad inserts you left on the table somehow jumps into your hands and slaps you in the face. Paper isn't supposed to do that.

Ads must *never* commandeer the user's browser. Pop-ups, overlays and lightboxes are cancerous. Eventually the hackers find a way to make these annoyances virulent, and we've then lost control over our computers and devices.