Microsoft Corp. is joining the trend of moving computing away from the desktop and onto the internet with Windows Azure, a service that will allow users to store their files and programs online.

Ray Ozzie, Microsoft's chief software architect, announced Azure at the company's professional developers conference on Monday. He said the platform will let the company sell computational ability and storage in an online "cloud." Azure users will be able to store fewer programs and files on their computers and access them online only when they are needed.

"Today marks a turning point for Microsoft and the development community,” he said. “The Azure services platform ... gives our customers the power of choice to deploy applications in cloud-based internet services or through on-premises servers, or to combine them in any way that makes the most sense for the needs of their business.”

Ozzie said users' files will be stored on servers in Microsoft data centres around the world, but he did not disclose when Azure would be available or at what price.

Azure evolved from a service announced by the company in April called Live Mesh, which was offered only to test users.

While some Microsoft products — such as the Hotmail e-mail application — provide online storage, the Redmond, Wash.-based company has generally resisted the trend toward "cloud computing" because the model threatens its main lines of business, which is selling disc-based software such as the Office suite of programs.

The company's main rival, Google Inc., has been pushing cloud computing for some time by offering its own free online versions of productivity software, such as word processors and spreadsheet applications.

Other internet companies such as Amazon.com and Salesforce have been pushing online storage and cloud computing as a way for businesses to slash their information technology budgets.

Many businesses have resisted the idea of cloud computing, however, because of the potential security risks associated with storing their data on another company's servers.