The Download: ChatGPT's origins, and making cement greener

Released in December as a web app by the San Francisco–based firm OpenAI, the chatbot exploded into the mainstream almost overnight. According to some estimates, it is the fastest-growing internet service ever, reaching 100 million users just two months after launch. Through OpenAI's $10 billion deal with Microsoft, the tech is now being built into Office software and the Bing search engine. Stung into action by its newly awakened onetime rival in the battle for search, Google is fast-tracking the rollout of its own chatbot, LaMDA. But OpenAI's breakout hit did not come out of nowhere.