Microsoft says its is undertaking a new global initiative to combat the "opportunity gap" for young people.

Philanthropically, the initiative is "the biggest step we've taken in the 37 years of the company," said Microsoft general counsel Brad Smith said.

Called YouthSpark, the program marks a new emphasis in Microsoft's philanthropic efforts, one that focuses on global youth programs. The company said it is investing $US500 million ($A481.26 million) in the initiative. Some of the money will be shifted from other charitable areas in which the company is involved worldwide, and some of the money will be new.

Taken altogether, that means Microsoft is committing the majority of its corporate cash giving to philanthropic efforts that support and serve youth.

YouthSpark is aimed at creating opportunities such as education, employment and entrepreneurship for about 300 million young people in 100 countries over the next three years.

Microsoft is partnering with hundreds of nonprofits worldwide in the effort.

The initiative will likely reach about 50 million people in the United States and about 250 million in the rest of the world, Mr Smith said.

Chief executive Steve Ballmer placed the initiative in the context of the "big, bold bets" Microsoft is making this year with the introduction of Windows 8 and other new products or upgrades. He said YouthSpark is another bet - one to close the "opportunity gap".

Mr Smith said the YouthSpark initiative does not change Microsoft's corporate giving focus in the Puget Sound area of Washington.

"We recognise this is our home state," he said.

Support for, say, local arts groups and hospitals is "definitely not going to be going down," he added.

The YouthSpark initiative is launching with three new programs:

-Give for Youth, a global microgiving marketplace.

-YouthSpark Hub, an online space where people can find out more about the programs and resources.

-Innovate for Good, a global, social online community geared toward connecting youths with each other.

Part of the initiative also involves donations of Microsoft products, including Office 365 for education, free tech tools for teachers and students and Skype in the classroom.