Microsoft Office 365 | Using office.com
Initially released as Office Web Apps in 2010, Office Online is a collection of Microsoft Office programs that are simplified and optimized to work with multiple Internet browsers. These changes make the software accessible from any device with a browser and an Internet connection, without the need for installing the software.
Office Online is free to use and allows multiple users to collaborate on the same file simultaneously. To use the service, you must be signed in with a Microsoft account.