designed to defend and uphold these principles.

\section{The Free Software Definition}

\label{Free Software Definition}

The Free Software Definition is set forth in full on FSF's website at

A particular program is Free Software if it grants a particular user of

that program, the following freedoms:

\begin{itemize}

Some people refer to software that gives these freedoms as ``Open

Source''.  Besides having a different political focus than those who call

it Free Software\footnote{The political differences between the Free

Software Movement and the Open Source Movement are documented on FSF's

website at

those who call the software ``Open Source'' are focused on a side issue.

User access to the source code of a program is a prerequisite to make use

of the freedom to modify.  However, the important issue is what freedoms

are granted in the license of that source code.  Microsoft's ``Shared

Source'' program, for example, gives various types of access to source

code, but almost none of the freedoms described in this section.

Software.  Additionally, such companies may contract with other companies

to commission software modification.

\subsection{The Freedom to Copy and Share}

Users may share Free Software in a variety of ways.  Free Software

age: choosing between obeying a software license, and friendship (by

giving away a copy of a program your friend who likes the software you are

using).  Free Software licenses, therefore, must permit this sort of

altruistic sharing of software among friends.

The commercial environment must also have the benefits of this freedom.

law\footnote{This statement is a bit of an oversimplification.  Patents

  and trade secrets can cover software and make it effectively non-free,

  one can contract away their rights and freedoms regarding software, or

  source code can be practically obscured in binary-only distribution

  without reliance on any legal system.  However, the primary control

  mechanism for software is copyright.}.  Copyright law, with respect to

software\footnote{Copyright law in general also governs ``public

  performance'' of copyrighted works.  There is no generally agreed

  definition for public performance of software and version 2 of the GPL

  does not govern public performance.}.  By law, the copyright holder (aka

the author) of the work controls how others may copy, modify and/or

distribute the work.  For proprietary software, these controls are used to

modification, and redistribution), removing the software from the

copyright system and placing it into the public domain does yield Free

Software.

Carefully note that software in the public domain is \emph{not} licensed

in any way.  It is nonsensical to say software is ``licensed for the

expressed permission to take actions governed by copyright law.

By contrast, what the copyright holder has done is renounce her copyright

controls on the work.  The law gave her controls over the work, and she

has chosen to waive those controls.  Software in the public domain is

absent copyright and absent a license.  The software freedoms discussed in

A legal mechanism is needed to redress this problem.  FSF was in fact

originally created primarily as a legal entity to defend software freedom,

and that work of of defending software freedom is a substantial part of

its work today.  Specifically because of this ``embrace, proprietarize and

extend'' cycle, FSF made a conscious choice to copyright its Free Software,

and then license it under ``copyleft'' terms, and many, including the

Copyleft is a legal strategy to defend, uphold and propagate software

freedom.  The basic technique of copyleft is as follows: copyright the

software, license it under terms that give all the software freedoms, but

use the copyright law controls to ensure that all who receive a copy of

the software have equal rights and freedom.  In essence, copyleft grants

systems (including GNU/Linux) to serve files to Microsoft Windows systems.

Two graduate students originally developed Samba in their spare time and

it was deployed non-commercially in academic environments.  However, very

soon for-profit companies discovered that the software could work for them

as well, and their system administrators began to use it in place of

Microsoft Windows NT file-servers.  This served to lower the cost of

The non-commercial users, however, were not concerned when these two

fellows began collecting paychecks off of their GPL'ed work.  They knew

that because of the nature of the GPL that improvements that were

distributed in the commercial environment could easily be folded back into

the standard version.  Companies are not permitted to proprietarize

This chapter begins the deep discussion of the details of the terms of

GPL\@.  In this chapter, we consider the core terms: GPL \S\S 0--3.  These

are the sections of the GPL that fundamentally define the legal details of

how software freedom is respected.

\section{GPL \S 0: Freedom to Run}

\S 0, the opening section of GPL, sets forth that the work is governed by

copyright law.  It specifically points out that it is the ``copyright

holder'' who decides if a work is licensed under its terms, and explains

how the copyright holder might indicate this fact.

seven or so), and reuse them as you with without licensing restrictions.

Fair use is a doctrine established by the courts or by statute.  By

contrast, unregulated uses are those that are not covered by the statue

nor determined by a court to be covered, but are common and enjoyed by

many users.  An example of unregulated use is reading a printout of the

how to be a better programmer.

\medskip

Thus, the GPL protects users fair and unregulated use rights precisely by

not attempting to cover them.  Furthermore, the GPL ensures the freedom

the Program''.  The reason this definition is particularly interesting is

not for the definition itself, which is rather straightforward, but the

because it clears up a common misconception about the GPL\@.

The GPL is often mistakenly criticized because it fails to give a

definition of ``derivative work''.  In fact, it would be incorrect and

fact, has no control over what may or may not be a derivative work.  This

matter is left up to copyright law, not the licenses that utilize it.

It is certainly true that copyright law as a whole does not propose clear

and straightforward guidelines for what is and is not a derivative

software work under copyright law.  However, no copyright license --- not

even the GNU GPL -- can be blamed for this.  Legislators and court

opinions must give us guidance to decide the border cases.

\section{GPL \S 1: Verbatim Copying}

GPL \S 1 covers the matter of redistributing the source code of a program

exactly as it was received.  This section is quite straightforward.

However, there are a few details worth noting here.

The phrase ``in any medium'' is important.  This, for example, gives the

that governs the modification controls of copyright law.  If someone

modifies a GPL'ed program, she is bound in the making those changes by \S

2.  The goal here is to ensure that the body of GPL'ed software, as it

continues and develops, remains Free as in freedom.

To achieve that goal, \S 2 first sets forth that the rights of

copying, as presented in \S 1.  Therefore, the details of charging,

keeping copyright notices intact, and other \S 1 provisions are in tact

here as well.  However, there are three additional requirements.

The first (\S 2(a)) requires that modified files carry ``prominent

notices'' explaining what changes were made and the date of such changes.

The goal here is not to put forward some specific way of marking changes,

or controlling the process of how changes get made.  Primarily, \S 2(a)

seeks to ensure that those receiving modified versions know what path it

took to them.  For some users, it is important to know that they are using

the standard version of program, because while there are many advantages

to using a fork, there are a few disadvantages.  Users should be informed

\medskip

The second requirement (\S 2(b)) contains the four short lines that embody

the legal details of ``share and share alike''.  These 46 words are

considered by some to be the most worthy of careful scrutiny.  It is worth