Many of the world’s largest Internet companies, like Google and Facebook, rely heavily on advertising to finance their online empires. But that business model is increasingly coming under threat, with one in five smartphone users, or almost 420 million people worldwide, blocking advertising when browsing the web on cellphones. That represents a 90 percent annual increase, according to a new report from PageFair, a start-up that helps to recoup some of this lost advertising revenue, and Priori Data, a company that tracks smartphone applications. The use of ad-blocking software has divided the online world. Supporters say it allows people to...
