Microsoft's flagship Office 2010 software suite has gone on sale worldwide to consumers.
The release concludes a long trial programme which saw details of its web-friendly features widely previewed.
Microsoft has also released cut-down versions of Office programs for the web and handsets that can be used by those who do not possess the "full" version.
Also included in Office 2010 are features that hook into popular social networking sites such as Facebook.
Office 2010 is being made available in a variety of formats suited to different groups of people. Microsoft said it expected the Home and Student version to sell for about £109 and the Professional edition for £429. Stand-alone versions of the programs making up Office are also available.
With Office 2010, Microsoft had worked hard to make a user's experience with the software as consistent as possible on the PC, web and mobiles, said Jacob Jaffe, a Microsoft spokesman. Web versions preserve the look and feel of documents and other files created with "full" versions of Office.
"It's important to have the same information show up no matter where and how I am accessing it," he said.
The web versions of the programs inside Office are immediately available to anyone who buys the software. Microsoft said ad-supported versions of these programs will be free to use for anyone with a Windows Live ID.
With the web versions of its popular programs, Microsoft is pitching itself into competition with rivals such as Google, Adobe and OpenOffice which offer web-based office software.
Despite the growth of these and other alternatives, Microsoft Office is still dominant inside businesses.
Microsoft said those that have been using the trial, or beta, version of Office 2010 can continue to use it until 31 October. At that point they can uninstall it in favour of a full version of the 2010 release, download a new trial or revert to an earlier version of Office.