[Trisquel-users] Re : How to check whether the software is free or not?

[lcerf]

The first thing to do is to check out the license it is distributed under.  
The mere name of the license may be listed in  
https://www.gnu.org/licenses/license-list.html that will tell you whether it  
is a free software license.

That said, it might be harder: software under a permissive license can depend  
on a proprietary library for instance; Linux, under the GNU GPL, includes  
blobs disguised as source code; etc. Also, be aware that a free software  
application may recommend proprietary software (for example Firefox  
recommends Adobe Flash).