When attempting to open an Office document from a SharePoint site, you might get an error that says:
"To open this document your computer must be running a supported version of Microsoft Word and a browser that supports opening files directly from the Office Web Apps"
Windows 7
The fix for this is simple. Please make sure that you are using the 32bit version of Internet Explorer and not the 64bit version. In your start menu, the 64bit version of Internet Explorer is identified as Internet Explorer (64bit) whereas the 32bt version of Internet Explorer is simply displayed as Internet Explorer. The 64bit version is the default for 64bit Windows 7 installations.
To select the 32bit version of Internet Explorer simply click on the start button and select the appropriate icon in start menu.
If you only see the 6bit version of Internet Explorer listed, click on the Start button and type Internet in the search field, and all versions of Internet Explorer should be listed. Right-click on the the appropriate icon and Pin to Start Menu or Pin to Taskbar to have the icon easily available.
Windows 10
You MUST use Microsoft Edge when connecting to SharePoint