Microsoft today announced a major expansion of its core Office productivity suite across mobile devices. Microsoft is replacing the limited Office app for the iPhone with three brand new apps, including Word, Excel, and PowerPoint. The apps allow iPhone users to create and edit Office content on their iPhones for free. Microsoft updated the iPad version of these three apps so there is continuity across them on the iOS platform. Further, Microsoft announced a new preview version of Office for Android tablets. This means most people will be able to work with Office documents on their mobile devices at no cost. Previously, Microsoft required a subscription to its Office 365 product. Moving forward, subscribers to Office 365 will have a more robust feature set, including advanced editing and collaboration tools, unlimited OneDrive storage, and Dropbox integration. Last, Microsoft said it is working on a touch-enabled version of Office for Windows 10. The new iPhone and iPad Office apps are free to download immediately. Android tablet owners can sign up for the Office preview beginning today.