Microsoft co-founder Bill Gates is back on top of the list of the world's richest people after a four-year hiatus.
Here's a look at key moments in Microsoft's history.
Here are some of the most pressing items on Nadella's to-do list as he reshapes Microsoft into a "mobile-first, cloud-first" company:
On Tuesday, Microsoft named Satya Nadella to replace Steve Ballmer as CEO. Ballmer had announced in August that he was planning to step down within a year. The CEO appointment is effective immediately.
Microsoft has named Satya Nadella, an executive in charge of the company's small, but growing business of delivering software and services over the Internet its new CEO. Company founder Bill Gates is also leaving the chairman role for a new role as technology adviser.
A lawsuit by Microsoft Corp. says an Iowa computer and information technology company sold computers with counterfeit Microsoft software.
Philanthropists Bill and Melinda Gates pitched an optimistic future for the world's poor and sick in their annual letter Tuesday, arguing passionately against three myths they say hurt efforts to bring people out of poverty, save lives and improve living conditions.
Ford Motor Co. shares rose while Microsoft Corp. stock fell Wednesday morning on news that Ford CEO Alan Mulally won't leave the automaker to lead the software giant.
Ford CEO Alan Mulally says he will not leave the automaker for Microsoft and will stay at Ford at least through 2014.
Microsoft says more than 2 million of its Xbox One consoles have been sold since the system's launch 18 days ago.
Microsoft Corp. says that more than 1 million Xbox One consoles have been sold worldwide since their midnight launch.
As the company begins selling its first new Xbox in eight years on Friday, some critics say Microsoft should spin the gaming unit off.
Microsoft chairman Bill Gates choked up while reading from prepared remarks during Steve Ballmer's final shareholders meeting as chief executive.
A former California technology analyst pleaded guilty Friday to insider trading charges in a cooperation deal with the government, admitting that he told secrets to an SAC Capital portfolio manager and others in 2009 about a blockbuster deal between Microsoft and Yahoo.
As part of an effort to become carbon neutral, Microsoft Corp. has entered a 20-year deal to buy power from a new wind farm in Texas, the first time the tech giant is directly purchasing electricity from a specific source.