Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
There are countless excellent open source software packages available today for virtually every taste and purpose, but it would be difficult to find a better exemplar of open source success than LibreOffice.
Having been born as a fork of OpenOffice.org back in 2010 following widespread community concern over Oracle's inherited stewardship of that popular package, LibreOffice has gone on to essentially replace its OpenOffice parent as the leading free and open Microsoft Office alternative.
OpenOffice still exists, to be sure, but it's LibreOffice that's now included with most Linux distributions, and it's LibreOffice that's being developed most actively.
In many ways, LibreOffice epitomizes the power of open source software.