FORTUNE — Mobile is the most profound development we will see in our lifetime, said Carolyn Everson, vice president of global marketing solutions at Facebook (FB), during Fortune’s Most Powerful Women Summit on Wednesday. “It’s transformational,” she added. For people in the world who still don’t have Internet access, it will come to them through their mobile devices rather then desktops.
Everson noted that a little more than a year ago Facebook’s business fundamentally changed. Southeast Asia and Africa had always seen more access to the social media platform via mobile, but last summer the curve switched in both Europe and the U.S. as well.
That’s a huge positive for Facebook, as people on average check their mobile devices 100 times a day, Everson said. It’s now instinctual. “It’s literally become as though we blink our eyes,” she added. “For our business that’s an incredible driver of growth.” From a marketing point of view, she said, the mobile device is now the most important screen.
MORE: Complete coverage of the Most Powerful Women Summit
China is a key example of this development. Jennifer Li, chief financial officer at Beijing-based search engine company Baidu (BIDU), said that 80% of China’s 590 million internet users are accessing the web via their mobile devices. And last year in July, user time spent on mobile surpassed desktops, and time on mobile is now double that of PCs.
“It’s important for businesses to recognize that trend,” Li noted. Baidu is working to educate advertisers on how to leverage the platform to catch the attention of consumers. She added, “We really have to hand-hold them and have to encourage them to build mobile friendly sites.”