Effective as of today, Microsoft's third CEO is officially Satya Nadella, a 46-year old engineer and former lead in Microsoft's cloud and enterprises divisions who has worked at the company for 22 years. Nadella introduces himself to Microsoft employees and the world with this letter. This appointment ends a months-long search for Steve Ballmer's replacement after the former CEO announced his retirement, with rumored contenders including Nokia's chief executive Stephen Elop and Ford CEO Alan Mulally. Also surprising is Bill Gates return to a more active role at Microsoft; the former CEO and Chairman takes a new title as Founder and Technology Advisor, promising to spend a third of his time meeting with product groups. Wired's profile on Nadella explains the new CEO's background and why he's more like Gates than Ballmer ever was.