Today about half the adults in the world own a smartphone, and there are as many subscriptions as people. In parts of the world without roads, landlines, postal service, newspapers, or banks, mobile phones are more than a way to share gossip and cat photos; they are a major generator of wealth. They allow people to transfer money, order supplies, track the weather and markets, find day labor, get advice on health and farming practices, even obtain a primary education.
