Microsoft is unveiling a new version of its widely used suite of word processing, spreadsheet and email programs.

A preview version of the new Office suite is being made available online at http://office.com/preview. CEO Steve Ballmer is introducing it at an event in San Francisco.

Like an upcoming redesign of Microsoft's Windows operating system, Office 15 will respond to touch as well as commands delivered on a computer keyboard or mouse. The addition of touch-based controls will enable Office to extend its franchise into the rapidly growing tablet computer market.