[caption id="attachment_10394" align="aligncenter" width="612"] Office on iOS.[/caption] After months of rumors, Microsoft is finally bringing Office to iOS devices. Microsoft Office Mobile for iOS requires a subscription to Microsoft’s Office 365, the company’s suite of cloud-based productivity software. Features include the ability to edit documents offline, review comments made on Word and Excel files, and share via email or SkyDrive and SharePoint. Supported devices include the iPhone 4 and subsequent generations (although Microsoft is emphasizing the software’s optimization for iPhone 5), the iPad Mini, and third- and fourth-generation iPads. Whatever the underlying hardware, Office for iOS requires iOS 6.1 or later. Microsoft’s release of Office for iOS comes a few days after the unveiling of iWork for iCloud, which offers Apple’s productivity software—Pages, Numbers, and Keynote—via the cloud. But Apple is a newcomer in the cloud-productivity space; Microsoft’s true challenger (at least for the moment) is Google Docs, now grouped within Google Drive. Google clearly wants to expand its cloud-productivity footprint, especially as it pertains to tablets and smartphones. Last summer, it acquired Quickoffice, a suite of cloud-based productivity software for mobile devices. A few months after that, in a proverbial shot across Microsoft’s bow, it issued an update that made it easier to convert legacy Office files into a version editable via Quickoffice. That’s in addition to continually improving the functionality and look of Google Docs. Microsoft couldn’t let its rivals make too many uncontested gains, and widening its Office presence to iOS—one of the world’s two most popular mobile operating systems—seems like a logical next step. Back in February, Morgan Stanley analyst Adam Holt estimated that Office for iOS could sell to approximately 30 percent of all iPad users; priced at $60 per copy, that comes to a grand total of $2.5 billion per year. In a January interview, Bloomberg asked Microsoft CEO Steve Ballmer about the prospect of Office on iOS. “I have nothing to say on that topic,” Ballmer said. “We have a product that we think makes a lot of sense. We do have a way for people always to get Office through the browser, which is very important. And we’ll see what we see in the future.” Now that the future’s here, the question is whether Office for iOS can help Microsoft maintain its strong presence in the productivity-software market, despite incursions from two of its biggest rivals.   Image: Microsoft