Microsoft's search engine launched in 2009 was Bing.
Bing officially launched on June 3, 2009, replacing Microsoft's previous search brand, Live Search. Microsoft promoted it as a “decision engine,” emphasizing features intended to help users compare information and act on results rather than simply locate webpages. The service inherited technology and experience from earlier products including MSN Search and Windows Live Search.
Bing introduced features such as search suggestions, related-search tools, and specialized results for images, video, maps, shopping, and travel. Microsoft also entered a major agreement with Yahoo! in 2009 under which Bing technology powered Yahoo Search results, although Yahoo retained its own consumer-facing brand.
The name can be confused with Google, Yahoo!, or DuckDuckGo because all are search engines. The question asks specifically for Microsoft's own service, not a company that used or partnered with Microsoft's search technology. Bing remains part of Microsoft's broader search and advertising business and later became associated with AI features such as Bing Chat.