LOS ANGELES — After more than two years as Microsoft’s low-profile chief software architect, Ray Ozzie finally has something to say: Windows Azure.

The man who replaced Bill Gates as Microsoft Corp.’s top technical thinker said Monday that Microsoft will compete with Amazon.com Inc., IBM Corp. and other rivals in selling information storage space and computing power “in the cloud,” distributed across massive data centers worldwide. The system, Windows Azure, will let companies and hobbyists alike build Web-based programs without having to invest in their own server farms.

Ozzie’s remarks at a Los Angeles conference for software developers indicated that after several years of disparate experiments, Microsoft is closer to a companywide strategy for coping with an upheaval in the software industry — the shift from powerful desktop programs to more lightweight, inexpensive ones that run over the Internet.

Nimbler Web companies such as Google Inc. have moved quickly to make programs that do much of the work of Microsoft’s cash-cow Office suite — but they do it over the Internet at little or no cost to the user, and can be updated frequently with new features and bug fixes.

Microsoft has largely fumbled this transition. In its “cloud” products before now, Microsoft has offered some of its business server software on a subscription basis and has cobbled together consumer Web services like e-mail and messaging under the “Live” brand.

Windows Azure is meant to be a broader “platform” for the cloud, much like Vista for PCs and Windows Mobile for phones and other devices. Microsoft’s own programs will run on it, as will those made by outside companies.

Ozzie said Microsoft has learned enough managing its own Web sites and programs, anticipating Web traffic spikes and lulls and ramping up or dialing down capacity, that it’s ready to market this expertise to others.

From the perspective of an average computer user, Ozzie said in an interview, Azure is another step toward solving the modern headache of accessing files from many different devices — for instance, home, work and portable computers and mobile phones.

Microsoft is letting software developers test Azure, but Ozzie emphasized that the system will change as more people kick the tires through 2009. He did not say when Microsoft will start selling access to Azure or how much it will cost.