Trisquel is a fully free (as in "free speech", not merely as in "free of charge") GNU/Linux based operating system. It is derived from Ubuntu, but includes only free software.
Trisquel has several editions, designed for different uses: the one called simply Trisquel ― the most important one ― is intended for home and personal use, and includes a lot of apps for that: networking, multimedia, office, games, etc.
The Edu edition is designed for educational centers, and allows the teacher to build a custom digital classroom within minutes.
The Pro edition is for enterprises, and includes accounting and business management software.
The Mini edition is for netbooks and older computers.