As an alternative to Microsoft’s Office suite (for Windows, Mac and Linux) there is an Open Source (free) alternative which comes in two flavours called LibreOffice (http://www.libreoffice.org/) and OpenOffice (http://www.openoffice.org/). While not quite as feature rich as Microsoft Office (so some tools and features aren’t compatible between them) you can open documents created in one application in the other (and also save as the others file format too).
Note: For anyone using the Linux operating system this will probably be your first choice of Office suite as Microsoft Office isn’t available on Linux.
- Text Guide: Commenting in LibreOffice (LibreOffice Help)
- Text Guide: Commenting in OpenOffice (Technical Communications Center)
- Video Guide: Commenting in OpenOffice (YouTube)