The inside story of how Amazon created Echo, the next billion dollar business no one saw coming

When Amazon executive Dave Limp first saw the pitch for the product that would become Echo in 2011, his main reaction was doubt. "This is going to be hard," Limp recalls thinking. But it would require a lot of inventions." The reaction was understandable given the lofty goals outlined in the Echo's original plan: it envisioned an intelligent, voice-controlled household appliance that could play music, read the news aloud and order groceries -- all by simply letting users talk to it from anywhere in the house. Since that time, the Echo has emerged as Amazon's sleeper hit, a hot-selling gadget that's being hailed as the standard-bearer for an entirely new computing paradigm in which Amazon suddenly has an edge on rivals such as Apple and Google.