[...] that the use of ad-blocking software grew 41 percent last year, with 198 million active users worldwide, according to a study conducted by Adobe and PageFair. This represents an existential threat to the $50 billion online advertising industry and has ignited a bitter feud between advertisers and developers of ad-blocking apps. On the sidelines, privacy advocates are pumping their fists for consumer choice while web publishers wring their hands over lost revenue.