Office Online is a collection of Office 365 hosted applications that work in a web browser. There are online versions of most of the desktop applications that provide a reduced, though useful set of the desktop application functions. These applications can be very useful if you are away from your normal computer and need to make a quick change to a document, access email or comment on a document produced by a co-worker.
To access the Office Online applications fire up your favourite browser such as Firefox, Chrome or Edge and logon to the Office 365 portal. Choose the application you want to use and you will be able access existing cloud storage documents or create new ones, read your mail and perform many other tasks.
There is no additional charge for the Office Online applications, they are free for all to use.