Office Online—previously known as Office Web Apps—is a free online version of Microsoft Office that includes Word, Excel, PowerPoint, and OneNote. Office Online is accessed through Microsoft's OneDrive—previously known as SkyDrive—a cloud-based storage service that allows you to create, upload, and share Office documents and other files.
Master the free, online version of Microsoft Office.
All About OneDrive and Office Online
Getting Started with OneDrive
Create and Share Office Documents
Upload, Sync, and Manage Files
Working with Office Online