Cortana is a virtual assistant developed by Microsoft, similar to Siri and Google Assistant. Named after an AI character in the popular Halo video game series, Cortana can perform a wide range of tasks including setting reminders, answering questions, and managing calendar events. Users can interact with Cortana through voice commands or text input on Windows devices. Cortana also integrates with other Microsoft services such as Outlook and Microsoft Edge for a more personalized experience. With its ability to learn from user interactions and preferences, Cortana aims to provide a seamless and intuitive virtual assistant experience.