A single-server Office Web Apps Server can support users of Exchange Server 2013, Lync Server 2013 and SharePoint Server 2013 viewing files stored on network shares enabling greater server utilization on the existing infrastructure.
The installation of Office Web Apps Server must be on a dedicated server. It can't be installed on an existing SharePoint Server. Servers can be added together to form a farm Office Web Apps to accommodate more connections, improve the user experience and high availability. The following are supported versions of the browser for viewing and editing of documents:
For an On-Premise environment during the creation of Office Web Apps Farm, the feature to edit documents can be enabled but this feature requires a separate license. Users of SharePoint Online and Office 365 have this feature enabled by default.
For users of Exchange Online preview of the feature is available by default. For users of Exchange 2013 On-Premise, it's a mandatory installation of Office Web Apps Server to view the files in OWA. This is a major change compared to Exchange Server 2010 that has the function of web-ready implemented internally, but Exchange 2013 requires the integration of Office Web Apps.
Below are the prints of an Excel file attached and its visualization in Office Web:
When this feature is enabled a separate portal on Office Web Apps Server is made available to create the access link for the documents Below is the print portal to generate the link to the file:
Below is an Excel file that is stored on a file server: