Since then, a lot of Free Software was developed and entire operating systems based only on Free Software were created. Unfortunately, some data is still stored in a format that is proprietary, secret and non-standard, made by corporations that want to retain control over the users of the software that generates such data.
The vrms program provides the facility for users of Debian-based Operating Systems (like Ubuntu Linux) to detect if their systems have any non-free software installed, so that the users can keep their computer "pure", without non-free software.
vrms can be installed using Synaptic Package Manager:
To execute it, just type "vrms" in the terminal and you will get the list of 'non-free' software installed on your system. For each program from 'non-free' installed, vrms displays an explanation of why it is non-free, if one is available. This explanation is usually from a list included in the vrms package itself, but other packages can provide additional lists of explanations, too.
So if you want a completely free (as in freedom!) operating system, you can use Use/ Install gNewsense instead of Ubuntu or others.