Bing Chat was Microsoft’s AI-powered conversational search experience, launched in February 2023 as a deeply integrated feature of Bing search, built on top of OpenAI’s GPT-4 model. It allowed users to have multi-turn conversations with an AI that retrieved live web results via the Bing index and synthesised them into cited, prose responses. Microsoft rebranded Bing Chat as Copilot in late 2023, positioning it as a unified AI assistant across Microsoft 365, Windows, and the Bing search engine. Copilot is powered by a combination of OpenAI models and Microsoft’s own infrastructure, and it cites sources from the Bing index alongside each answer. For SEO practitioners, Bing Chat and its successor Copilot are significant because they represent one of the largest deployed AI answer surfaces outside of Google, meaning that Bing search ranking indirectly influences which content is retrieved and cited in Copilot responses. Bing’s market share growth after the Copilot launch made Bing SEO more commercially relevant than it had been in years.