Office Web Apps are web based versions of Microsoft Office 2010. As they are hosted in the “cloud”, i.e. the programs haven’t been installed on your computer, the functionality that Office Web Apps provide is limited. However, they do offer a look and feel that is consistent with their desktop counterparts.
The Excel Web App is the web based equivalent of Office Excel 2010 and is freely available to anyone who has an internet connection and a browser. As you can imagine, because functionality is restricted, the ribbon in the Excel Web App holds fewer commands and functions than that found in Excel 2010. For those new to Microsoft Office, the ribbon is the replacement to the file and menu system found in versions of Office prior to the 2007 version.
Here is the ribbon in The Excel Web App.
Note that the only tabs displayed on this ribbon are: