Many of the people who read this article will do so because Greg Marra, 26, a Facebook engineer, calculated that it was the kind of thing they might enjoy.
Mr. Marra’s team designs the code that drives Facebook’s News Feed ”” the stream of updates, photographs, videos and stories that users see. He is also fast becoming one of the most influential people in the news business.
Facebook now has a fifth of the world ”” about 1.3 billion people ”” logging on at least monthly. It drives up to 20 percent of traffic to news sites, according to figures from the analytics company SimpleReach. On mobile devices, the fastest-growing source of readers, the percentage is even higher, SimpleReach says, and continues to increase.