Free Software: an Overview

History, importance and advantages of Free (Open source) Software. Technical, economical, legal and social issues.

Last significant update : 26 August 2005

1 What is Free Software ?

2 Definition

Free software is a matter of the users' freedom to run, copy, distribute, study, change and improve the software.

Free software is not a matter of price (it is, but that's secondary).

3 Definitions

Proprietary software
Use, modification and/or redistribution are forbidden or restricted.
No license fee. Distribution is generally allowed, but modification is generally forbidden.
Users are required to pay a license fee after some time of use without any cost.
Semi-free software
Free software for non-profit purposes only.
Public domain software
Software which is not protected by copyright.

Copyright is a set of exclusive rights (with exceptions) granted to the authors of creative works (literary or musical works, movies, sound recordings, paintings, photographs or software, ...).
These rights to use, perform, reproduce, sell or adapt the work are granted to the authors for a limited time after which the work passes into the public domain.

The holder of a copyright can require that a license be accepted as a condition of being allowed to use, reproduce, or modify the licensed work.

A software license defines the authorised uses The use of a software program which has not yet passed into the public domain is therefore restricted to the uses authorized by its license.

5 Copyleft

It is not forbidden to appropriate public domain software, that is to sell users something which belonged to them in the first place.

Copyleft imposes that anyone who redistributes the software, with or without changes, must pass along the freedom to further copy and change it.

Copyleft uses copyright law to guarante that every user has freedom.

The most widespread copyleft software license is the GNU General Public License (GPL) of the Free Software Foundation.

6 The availability of source code

Executable code

Machine, binary language.

00101101 01101100 00101101 01101100 01010011 11001011 01010011 11001011
00011001 00111100 00011001 00111100 11000101 10100101 11000101 10100101
00101101 01101100 00101101 01101100 01010011 11001011 01010011 11001011
00011001 00111100 00011001 00111100 11000101 10100101 11000101 10100101
Source code

Human readable language.

#include <stdio.h>
int main(void) {
  int count;
  for (count=1 ; count<=500 ; count++) {
    printf("I shall not throw paper planes in class.\n");
  return 0;

Source code -> binary code = Compilation

Binary code -> Source code = Reverse engineering, often forbidden => black box

The availability of source code is a necessary condition (but not a sufficient condition) for Free software.

7 Categories of Free and Non-Free Software

Categories of Free and Non-Free Software

8 Historical perspective

9 History

1960s IBM has 70 to 80% of the world's harware and software market, and invents the notion of series of compatible computers.
1965 DEC manufactures the first mini-computers.
1969 First version of the Unix operating system.
1971 Intel sells the first microprocessors.
1973 The first micro-computers.
1981 IBM lauches the Personal Computer (PC) and makes micro-computers respectable. It's operating system is Microsoft MS/DOS.
1984 Apple launches the Macintosh, with the first general public graphical user interface.
1984 Beginning of the GNU project.
1990 Windows 3.0.
1991 The development of Linux begins.
1994 Version 1.0 of Linux.
1998 Open Source Initiative.

10 From Free Software to Free Software

1960s Software is Free, although the expression doesn't exist yet.
1969 Unbundling of hardware and software (and services) pricing by IBM, under the threat of an antitrust lawsuit.
1976 An Open Letter to Hobbyists, Bill Gates: most of you steal your software. Hardware must be paid for, but software is something to share. Who cares if the people who worked on it get paid ?
1980s Software becomes more and more proprietary.
1984 GNU project.
1991 Linux.
1993 Debian GNU/Linux
1998 Open Source Initiative.

11 The GNU project

Levitating, Meditating, Flute-playing Gnu

Recursive acronym for "GNU's Not UNIX" pronounced "guh-noo" (audible g).

1984, Richard M. Stallman (RMS)


Free as in Freedom

12 The Free Software Foundation

A GNU Head

Mission: Preserve, protect and promote the freedom to use, study, copy, modify, and redistribute computer software, and defend the rights of Free Software users.

13 Open Source Initiative

1998 : Initiative to promote Free software under the name of Open Source software:

Open Source Initiative (OSI) is a non-profit corporation which:

14 Free or Open Source ?

15 The Open Source Definition

  1. Free Redistribution
  2. Source Code
  3. Derived Works
  4. Integrity of The Author's Source Code
  5. No Discrimination Against Persons or Groups
  6. No Discrimination Against Fields of Endeavor
  7. Distribution of License
  8. License Must Not Be Specific to a Product
  9. License Must Not Restrict Other Software
  10. License Must Be Technology-Neutral

16 Free as in Freedom

Free software
Open Source software

17 Free and Open Source

Open Source software is Free Software, and Free software is Open Source software.

Different approaches:

( This does not mean that the Free software movement, which promotes copyleft, is not pragmatic. )

The OSI's definition of Open Source in one paragraph is similar to the definition of Free software of the FSF:

Open source promotes software reliability and quality by supporting independent peer review and rapid evolution of source code. To be OSI certified, the software must be distributed under a license that guarantees the right to read, redistribute, modify, and use the software freely.

18 Categories of Free and Non-Free Software

Categories of Free and Non-Free Software

19 GNU/Linux

20 Linux : a kernel and the most famous piece of Free software

Kernel: the core of an operating system (manages hardware...).

By 1990, the GNU operating system was almost complete; the only major missing component was the kernel.

1991, Linus Torvalds: I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones.

Linux was quickly released under the GNU GPL, and got to version 1.0 in 1994!

One should talk about the Linux kernel, and the GNU/Linux operating system.

Linux is also emblematic of the success of the Free software development model.

21 GNU/Linux

The Dynamic Duo: The Gnu and the Penguin in flight
The Dynamic Duo: The Gnu and the Penguin in flight :

22 Distributions

While Windows and MacOS have a single distributor, GNU/Linux can be built from scratch, and is available from various vendors.

Distribution =

= a set of packages (software components) including an installation and update system.

There are many distributions, suited fo various uses.

23 Debian GNU/Linux

Logo Debian

THE free distribution.

Debian has an exemplary social contract, and the Debian Free Software Guidelines have been used as a model for the Open Source Definition

Debian has been growing and improving since 1993.

24 Debian Developers

25 Networked organisations

26 Free Software and the Internet

Internet = network of networks

The cooperative functioning of Free software:

The Internet has always mostly worked with Free software:

27 The Cathedral and the Bazar

Before Linux, most experts thought that software, beyond a significant size, could only be built as cathedrals, that is designed by a few experts, et with a strict hierarchy (pyramidal structure). The development of Linux is open to everybody, and looks like a bazar (networked structure).

The success of Linux surprised Eric S. Raymond. The Cathedral and the Bazar analyses what he has learnt from Linux in the practice of the management of the Free software project fetchmail. Some of his conclusions are technical. Here are a few others:

28 Interoperability and Free Competition

29 De-jure and de-facto standards

Standardization is both the best and the worst thing. It may slow down innovation, but it allows interconnection.

Interoperability: Compatibility of hardware and software.

De-facto standards may be:

30 Examples : Web browsers and file formats

The Browser War

Netscape and Internet Explorer were successively dominant. As competitors, they were innovating. Dominant, they have blocked the development of the Web.

File Formats

File formats ought to be open standards:

31 Free Software, Standards and Innovation

Dominant proprietary standards block or even eliminate free competition. In an industry like software, innovation is both:

Competition becomes combat when the competitors begin trying to impede each other instead of advancing themselves. Innovation requires free competition.

32 Free Software and Economy

33 Software is a peculiar immaterial asset

Software is an immaterial asset:

Like information and knowledge, software is a peculiar asset:

34 Selling Free Software

35 The Magic Cauldron

37 Intellectual Property

Fair use: citation, private copy, freedom of speech.

38 The Predominance of Copyright and the Patent Weapon

When software has become a commercial asset, in the 1970's, its legal protection has converged towards the use of existing tools, and the predominance of copyright.

Copyright protects the expression of an idea. The protection of software by copyright allows its use only within the scope of its license, but it doesn't forbid making similar and/or compatible software.

However, there's been a dramatic increase in the number of software patents in the United States since the 1980's ; but also in Europe, whereas software patents are clearly forbidden!

Software patents are a threat against interoperability, innovation, and free competition:

If people had understood how patents would be granted when most of today's ideas were invented and had taken out patents, the industry would be at a complete standstill today. Bill Gates.

The solution is patenting as much as we can. A future startup with no patents of its own will be forced to pay whatever price the giants choose to impose. That price might be high. Established companies have an interest in excluding future competitors. Bill Gates.

39 Licenses

Characteristics of the main Free software licenses; and estimates of their use by the French administration, based on the 26552 projects hosted by in June 2002.
License Open Source Free Copyleft GPL compatible Estimates in 2002
GNU General Public License (GPL) yes yes yes yes 73 %
GNU Library/Lesser General Public License (LGPL) yes yes yes yes 10 %
BSD License (original) yes yes no no 7 %
BSD License (modified) yes yes no yes
Apache Software License yes yes no no
Mozilla Public License yes yes partly no

40 The GNU General Public License

Certains disent que la licence GNU GPL est contagieuse. Les libertés associées aux logiciels qu'elle protège sont contagieuses.

41 Free Software and Society

42 Trusted Computing ?

Who should your computer take its orders from? With a plan they call "trusted computing", large media corporations, together with computer companies, are planning to make your computer obey them instead of you.

"Treacherous computing" is a more appropriate name.

43 The Future of Ideas

"Free Culture" is the title of an enlightening conference by Lawrence Lessig, a lawyer. It's refrain is:

The same lawyer about the Internet:

When the content layer, the logical layer, and the physical layer are all effectively owned by a handful of companies, free of any requirements of neutrality or openness, what will you ask then? » Lawrence Lessig

44 Homesteading the Noosphere

In Homesteading the Noosphere, Eric S. Raymond analyses the hacker culture as a gift culture: Social status is determined not by what you control but by what you give away.

"real" programmer

The hacker ethic according to Steven Levy in Hackers:Heroes of the Computer Revolution:

45 A Model, several Models

A model ?

Several models thanks to freedom, diversity, planetary scale:

46 Free Resources

47 Why One Should Choose Free Software

48 Advantages

49 Freedom, Equality, Fraternity

And Responsibility.