Microsoft has not released a version of the Office software for Apple's iPad tablets. It has also decided not to offer the products on Android devices, a move that is designed to drive consumers to Windows based devices.
The US software Company has redesigned Word, Excel, PowerPoint and Outlook to work better with touch-screen-controlled computers and tablets. They have also integrated Skype into the new Office offering.
In an effort to take on Dropbox and Google's Drive, Microsoft says it has made it easier for teams to share PowerPoint presentations via SkyDrive.
The retooled software offers a touch mode that makes several of its controls bigger so they are more finger-friendly, and they've incorporated friendly gestures such as swipe and pinch-and-zoom. Files can also be viewed in "read mode", which displays them in a format that particularly suits tablets.
By default, files are saved to the firm's SkyDrive cloud storage facility, although users can choose to save them on their hard drive if they wish.
Last year Microsoft generated $24bn; a third of the firm's revenue from their Microsoft Office Suite.
The Office 365 Home Premium will be sold on a subscription basis at $119 a year. That includes five licences for use on Windows PCs or Apple Macs. Office Home and Student for one PC will sell for $169 (Word, Excel, PowerPoint and OneNote only), Office Home and Business for $299 (adds Outlook), and Office Professional for $599.
Recent studies reveal users are switching to the new Windows 8 at a slower rate than they adopted Windows 7 and Windows Vista.
Users wanting additional plug-ins can get them from a new Office Store. These include the ability to add Twitter functionality to the Outlook email tool and to consult Encyclopaedia Britannica articles from within Word.
Many of these are free, although US firm Sensei Project Solutions is among the first to charge a fee, for its "task analyser", which is designed to identify problems or missing information in users' documents.
Read mode allows users to navigate through a document by tapping arrows on either side of its columns of text.
A version of the online Office 365 apps for businesses is due for release on 27 February.