The obvious choice of Office tools if you are a firm believer in open source, LibreOffice was a fork from the original OpenOffice years ago (itself an offshoot of StarOffice). Inside are word processor, spreadsheet, and presentations programs, a vector graphics editor, a math formula editor, and a database. It's a little more awkward to use than the desktop version of Microsoft Office, but you can't beat the price. Grab the LibreOffice Viewer app for Android to look at files.
Distribution of source code. One of the problems with most proprietary software is that you can't fix bugs or customize it since the source code is not available. Also, the company may decide to stop supporting the hardware you use. Many free licenses force the distribution of the source code. This protects the user by allowing them to customize the software for their needs.
Free software is generally available at no cost and can result in permanently lower TCO costs compared to proprietary software. With free software, businesses can fit software to their specific needs by changing the software themselves or by hiring programmers to modify it for them. Free software often has no warranty, and more importantly, generally does not assign legal liability to anyone. However, warranties are permitted between any two parties upon the condition of the software and its usage. Such an agreement is made separately from the free software license.