Microsoft launched Tay, an experimental chatbot, on Twitter. Given the persona of an American teenager, it was designed to get better at conversation by learning from its interactions. Almost immediately, users deliberately exploited the fact that Tay would mimic and repeat what was said to it, flooding it with racist, sexist, anti-Semitic, and politically extreme content. Within 16 hours it had posted more than 95,000 times, a substantial share of it abusive. Microsoft pulled Tay from Twitter in under 24 hours, deleted many of the posts, and apologized, acknowledging that it had not anticipated coordinated misuse and saying it would review its development process. It was the earliest and starkest demonstration of what happens when a learning system is placed in public, and it impressed on the industry the need for red-teaming and staged release. It is still cited as one reason OpenAI was cautious in how it released ChatGPT.