The company’s embrace of OpenAI’s technology has seen Microsoft endanger some existing search ad revenue by prominently promoting a chat box in Bing results. The tactic has ended up being a key driver of Bing chat usage. “We are being, I would say, innovative and taking some risks,” Mehdi says.

At the same time, Microsoft has held back from going all-in on OpenAI’s technology. Bing’s conversational answers do not always draw on GPT-4, Ribas says. For prompts that Microsoft’s Prometheus system judges as simpler, Bing chat generates responses using Microsoft’s homegrown Turing language models, which consume less computing power and are more affordable to operate than the bigger and more well-rounded GPT-4 model.

Peter Sarlin, CEO and cofounder of Silo AI, a startup developing generative AI systems for companies, says he suspects penny pinching explains why he has noticed Bing’s initial chat responses can lack sophistication but follow-up questions elicit much better answers. Ribas disputes that Bing chat’s initial responses can be of lower quality, saying that users’ first queries can lack context.

Bing has not traditionally been a trendsetter in search, but the launch of Bing chat prompted competitors to hustle. Google, which abandoned a more cautious approach, China’s Baidu, and a growing bunch of startups have followed with their own search chatbot competitors.

None of those search chatbots, nor Bing chat, has garnered the buzz or apparently the usage of OpenAI’s ChatGPT, the free version of which is still based on GPT-3.5. But when Stanford University researchers reviewed four leading search chatbots, Bing’s performed best at backing up its responses with corresponding citations, which it does by putting links at the bottom of chat responses to the websites from which Prometheus drew information.

Microsoft is now fine-tuning its new search service. It's giving users more options, trying to make vetting answers easier, and starting to generate some revenue by including ads. Weeks after Bing chat launched, Microsoft added new controls that allow users to dictate how precise or creative generated answers are. Ribas says that setting the chatbot to Precise mode yields results at least as factually accurate as does a conventional Bing search.

Expanding Prometheus’ power helped. Behind the scenes, the system originally could ingest about 3,200 words of content from Bing results each time it performed a search before generating a response for a user. Soon after launch, that limit was increased to about 128,000 words, Ribas says, providing responses that are more “grounded” in Bing’s crawl of the web. Microsoft also took feedback from users clicking thumbs-up and -down icons on Bing chat answers to improve Prometheus.

Two weeks in, 71 percent of the feedback was thumbs up, but Ribas declines to share fresher information on Microsoft’s measures of user satisfaction. He will say that the company is getting a strong signal that people like the full range of Bing chat’s capabilities. Across different world regions, about 60 percent of Bing chat users are focused on looking up information, 20 percent are asking for creative help like writing poems or making art, and another 20 percent are chatting to no apparent end, he says. The art feature, powered by an advanced version of OpenAI’s DALL-E generative AI software, has been used to generate 200 million images, Microsoft CEO Nadella announced yesterday.