\item The business advantages that the GPL provides.

  \item The most common business models used in conjunction with the GPL.

  \item How existing GPL'd software can be used in existing enterprises.

  \item The basics of the Lesser GPLv2.1 and Lesser GPLv3, and how they

    differs from the GPLv2 and GPLv3, respectively.

  \item The basics to begin understanding the complexities regarding

    derivative and combined works of software.

\end{itemize}

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% END OF ABSTRACTS SECTION

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% START OF DAY ONE COURSE

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\chapter{What Is Software Freedom?}

Study of the GNU General Public License (herein, abbreviated as \defn{GNU

  GPL} or just \defn{GPL}) must begin by first considering the broader world

of software freedom. The GPL was not created from a void, rather, it was

created to embody and defend a set of principles that were set forth at the

founding of the GNU project and the Free Software Foundation (FSF) -- the

organization that upholds, defends and promotes the philosophy of software

freedom. A prerequisite for understanding both of the popular versions of GPL

(GPLv2 and GPLv3) and their terms and conditions is a basic understanding of

the principles behind it.  The GPL family of licenses are unlike almost all

other software licenses in that they are 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

\verb0http://fsf.org/0 \verb0philosophy/free-sw.html0. This section presents

an abbreviated version that will focus on the parts that are most pertinent

to the GPL\@.

A particular program grants software freedom to a particular user if that

user is granted the following freedoms:

\begin{itemize}

\item The freedom to study how the program works, and modify it

\item The freedom to redistribute copies.

\item The freedom to distribute copies of  modified versions to others.

\end{itemize}

The focus on ``a particular user'' is particularly pertinent here.  It is not

uncommon for the same version of a specific program to grant these freedoms

to some subset of its user base, while others have none or only some of these

freedoms.  Section~\ref{Proprietary Relicensing} talks in detail about how

this can unfortunately happen even if a program is released under the GPL\@.

Many 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 Web site at

  {\tt http://www.fsf.org/licensing/essays/free-software-for-freedom.html}.}

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

issue.  Specifically, 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.

Software freedom is only complete when no restrictions are imposed on how

these freedoms are exercised.  Specifically, users and programmers can

exercise these freedoms noncommercially or commercially.  Licenses that grant

these freedoms for noncommercial activities but prohibit them for commercial

activities are considered non-free.  Even the Open Source Initiative

(\defn{OSI}) (the arbiter of what is considered ``Open Source'') also rules

such licenses not in fitting with their ``Open Source Definition''.

In general, software for which most or all of these freedoms are

restricted in any way is called ``non-Free Software.''  Typically, the

term ``proprietary software'' is used more or less interchangeably with

``non-Free Software.''  Personally, I tend to use the term ``non-Free

Software'' to refer to noncommercial software that restricts freedom

(such as ``shareware'') and ``proprietary software'' to refer to

commercial software that restricts freedom (such as nearly all of

Microsoft's and Oracle's offerings).

Keep in mind that the none of the terms ``software freedom'', ``open source''

and ``free software'' are not known to be trademarked by any organization in

any jurisdiction.  As such, it's quite common that these terms are abused and

misused by parties who wish to bank on the popularity of software freedom.

When one considers using, modifying or redistributing a software package that

purports to be Open Source or Free Software, one \textbf{must} verify that