Ads pop up and play automatically, daring readers to shut them down with feats of fine motor control. The ads commandeer the screen. They expand and contract. They cover the text and refuse to budge.
And then there is the dreaded X — the one that invites you to close the ad yet seems impervious to repeated clicks of the cursor or the jabs and thrusts of even the most powerful fingers. (Perhaps you have tried a hammer?)