From the article: "In a nutshell, zero-rating plans exempt particular data from counting against a user's data cap, or from accruing any excess usage charges.<p>The most dangerous of these plans, such as the AT&T and Verizon offerings, only offer their users zero-rated data from content providers who pay the carriers money to do so.<p>Such “pay for play” arrangements favor big content providers who can afford to pay for access to users' eyeballs, and marginalize those who can't, such as nonprofits, startups, and fellow users."