Microsoft on Monday unveiled Windows Phone 8, the new version of its smartphone operating system, representing the software giant's latest move to challenge the market leaders of Apple and Google.

The new smartphone software has a Start screen in the form of square tiles, which can display real-time information such as updates on social networking sites.

Users can personalize the Start screen by pinning their favorite items such as application, photos, and choose from three sizes and 20 colors for the so-called "Live Tiles."

At a media event held in San Francisco, the US state of California, Microsoft executives touted new users-friendly features including "Data Sense," which helps users conserve their data allowance through ways such as compressing Web images.

"Our way is to put people at the center of the experience, not icons for apps," Joe Belfiore, corporate vice president of Windows Phone Program Management at Microsoft, said at the event.

The smartphone software shares the same user interface and technology core with Windows 8, Microsoft's newly-launched operating system for personal computers and tablet computers, which makes it easier for developers to create apps for both platforms and for users to run similar programs across different devices.

Windows Phone 8 also offers support for hardware specifications including multi-core processors and near-field communication (NFC), a technology that allows users to pay with their smartphones or connect their phones to other NFC-enabled devices.

Major mobile carriers in the United States including Verizon Wireless, AT&T and T-Mobile will start selling handsets running Windows Phone 8 made by Nokia, HTC and Samsung in the coming weeks, according to Microsoft.

Microsoft CEO Steve Ballmer speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on October 29, 2012. Photo: Xinhua

Microsoft CEO Steve Ballmer speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on October 29, 2012. Photo: Xinhua

Microsoft CEO Steve Ballmer speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on October 29, 2012. Photo: Xinhua

Joe Belfiore, corporate vice president of Windows Phone Program Management at Microsoft, speaks at a special media event to announce the next generation Windows Phone, Windows Phone 8, at the Bill Graham Auditorium in San Francisco, the United States, on October 29, 2012. Photo: Xinhua