Trisquel GNU/Linux: a 100% free (as in freedom) operating system
Trisquel is a GNU/Linux operating system that only offers free (non proprietary) software.
There are several Trisquel editions for old or new computers: Trisquel Mini (LXDE), Trisquel (MATE), Triskel (KDE) and Trisquel Sugar. There is also a NetInstall edition. I have tested Trisquel 10.0 LTS.
Trisquel is based on Debian but it has its own repositories with only free software (20,000 packages). Due to this, you must ensure that your computer does not need proprietary drivers to work properly. There is a graphical package manager already installed but it does not show all available packages (like Firefox).
Installed packages (on MATE edition) include: Abrowser (web browser based on Firefox), LibreOffice, GIMP, VLC and Transmission, among other popular software.
Regardless of its ‘100% free’ nature, Trisquel is a great system for anyone (special mention for its Mini edition, it’s a really lightweight system).