In free software, this means without using a single program that you cannot study and modify, and above all share with our friends and colleagues.
At that time, until the 1970s, computers were very large machines used in the army, large companies and universities.
So at that time, manufacturers were selling these huge machines. And the programs to run them were minimalist. These programs were supplied with the machines and left to the researchers to run them.
So, a salesman like IBM could easily put his customers in touch so that they could manage these programs themselves and make them evolve according to their needs. Mutual assistance was therefore rather the norm.
However, towards the beginning of the 1980s, microcomputers (known as PC) and "desktop" printers appeared. And with them came a new relationship between the vendors and their programmes.
From now on, each device came with floppy disks containing programs to run it, but also with restrictions on use and sharing. This is called a user licence, a sort of contract between the seller and his customers.
Now, two departments at the same university can no longer lend each other floppy disks for their printers, even if they have bought the same model.
A disruption in university usage.
It didn't take more than that to revolt at least one of them, Richard Stallman, and launch the project of a completely free position.
After several years of intense programming, all the basics of the project were there. A fairly complete set of fundamental programmes for the daily use of a micro-computer, at least for an engineer at the time. All the basics, except for one called the kernel. It's a very technical part, invisible, but essential.
At the same time, a kernel programme launched by a student, Linus Torvalds, had gone from curiosity and entertainment to a satisfactory state of maturity.
Moreover, this project had adopted the participatory principle and the licence of free software. And, with the necessary adaptations, the GNU project team was able to use this kernel to complete a first autonomous, usable and entirely free software package. The first GNU/Linux package was born.
The project is still active, benefiting from a large number of contributors from all over the world and relying on a foundation that was created in the early years, the Free Software Foundation.
There are now several presentations of the GNU system, unfortunately often referred to as "linux distributions": Ubuntu, Debian, Red Hat, Mandriva, Mint and many others.
Many programs, without being directly part of the GNU project, have adopted the philosophy of free software. Among the best known are
Android (only part of it is free software)
Mozilla Firefox
Mozilla Thunderbird
VLC
LibreOffice / OpenOffice
Gimp
PHP, mysql, apache
Wordpress, Spip, Drupal, Joomla
In addition, much of the Internet is based on free software and open formats. Without them, the Internet could not exist.
This is the case, in particular, of the essential system that allows an Internet address, as here, "nonviolent.eu", to be associated with the corresponding server - the Domain Name System (DNS).
Incidentally, the GNU project was thus the starting point of the free software movement, which some call open source in reference to its openness, but often forgetting the values on which the FS.
Moreover, the free software movement has been one of the sources of inspiration for the common people's movement, which puts the emphasis on everything that should be considered or developed as patriotic to humanity, such as water, public services, etc...
And of course, the FS movement inspired Jimmy Wales and Larry Sanger to create Wikipedia.