As part of its Windows Phone 8.1 update announcement Wednesday, Microsoft introduced Cortana, a personal digital assistant with a persona.

“We were inspired by the popular character from Halo who served as a brilliant AI and a deeply personal digital assistant to Master Chief… so we called her Cortana,” said Joe Belfiore, the corporate vice president and manager for Windows Phone Program Management at Microsoft on his blog.

Explains Belfiore: “Powered by Bing, Cortana is the only digital assistant that gets to know you, builds a relationship that you can trust, and gets better over time by asking questions based on your behavior and checking in with you before she assumes you’re interested in something. She detects and monitors the stuff you care about, looks out for you throughout the day, and helps filter out the noise so you can focus on what matters to you.

“Cortana will launch shortly here in the U.S. first as a “beta,” and then will launch in the US, the U.K. and China in the second half of 2014 with other countries to follow afterwards into 2015.”

The Verge has a more detailed description of Cortana.