At its Build developer conference, Microsoft introduced Cortana, a voice-driven digital assistant shipping with Windows Phone 8.1. Built on the Bing search engine, it was designed to learn from a user's behavior and ask questions before assuming what they wanted; the name came from the AI character in the game Halo. Following Apple's Siri and Google's voice assistant, it represents the era of talk-to-it AI before generative models. Cortana was later wound down, and from 2023 Microsoft's assistant strategy was replaced by Copilot.