to include an explicit provision setting forth the duration of the rights

being granted. In other countries, including the USA, such a provision is

unnecessary but permissible.

GPLv3~\S2\P1 also acknowledges that licensees under the GPL enjoy rights of

copyright fair use, or the equivalent under applicable law.  These rights are

compatible with, and not in conflict with, the freedoms that the GPL seeks to

protect, and the GPL cannot and should not restrict them.

However, note that (sadly to some copyleft advocates) the unlimited freedom

to run is confined to the \textit{unmodified} Program.  This confinement is

unfortunately necessary since Programs that do not qualify as a User Product

in GPLv3~\S6 (see \S~\ref{user-product} in this tutorial) might have certain

unfortunate restrictions on the freedom to run\footnote{See

  \S~ref{freedom-to-run} of this tutorial for the details on ``the freedom to

  run''.}

GPLv3~\S2\P2 distinguishes between activities of a licensee that are

permitted without limitation and activities that trigger additional

requirements.  Specifically, GPLv3~\S2\P2 guarantees the basic freedoms of

privately modifying and running the program.

Also, GPLv3~\S2\P2 gives an explicit permission for a client to provide a

copy of its modified software to a contractor exclusively for that contractor

to modify it further, or run it, on behalf of the client.  However, the

client can \textit{only} exercise this control over its own copyrighted

changes to the GPL-covered program.  The parts of the program it obtained

from other contributors must be provided to the contractor with the usual GPL

freedoms.  Thus, GPLv3 permits users to convey covered works to contractors

operating exclusively on the users' behalf, under the users' direction and

control, and to require the contractors to keep the users' copyrighted

changes confidential, but \textit{only if} the contractor is limited to acting

on the users' behalf (just as the users' employees would have to act).

The strict conditions in this ``contractors provision'' are needed so that it

cannot be twisted to fit other activities, such as making a program available

to downstream users or customers.  By making the limits on this provision

very narrow, GPLv3 ensures that, in all other cases, contractors gets the

full freedoms of the GPL that they deserve.

GPLv3~\S2's final paragraph includes an explicit prohibition of sublicensing.

This provision ensures that GPL enforcement is always by the copyright

holder.  Usually, sublicensing is regarded as a practical convenience or

necessity for the licensee, to avoid having to negotiate a license with each

licensor in a chain of distribution.  The GPL solves this problem in another

way --- through its automatic licensing provision found in GPLv3\~S10 (which

is discussed in more detail in \S\~ref{GPLv3s10} of this tutorial).

Technological measures to defeat users' rights --- often described by such

Orwellian phrases as ``digital rights management,'' which actually means

limitation or outright destruction of users' legal rights, or ``trusted

computing,'' which actually means selling people computers they cannot trust

--- are alike in one basic respect.  They all employ technical means to turn

the system of copyright law, where the powers of the copyright holder are

limited exceptions to general freedom, into a prison, where everything not

specifically permitted is utterly forbidden, and indeed, if the full extent

of their ambition is realized, would be technically impossible.  This system

of ``para-copyright'' has been created since the adoption of GPLv2, through

legislation in the United States, the European Union, and elsewhere that

makes it a serious civil or even criminal offense to escape from these

restrictions, even where the purpose in doing so is to restore the users'

legal rights that the technology wrongfully prevents them from exercising.

% FIXME: Remove FSF specific parts

As a digital rights organization, we would not be following our mission if we

did not oppose these injustices.  But the reason our license must respond to

these practices at all is the result of a remarkable irony. Those who wish to

impose DRM on the public would like to do so by using software covered by the

GPL, a license that is intended to preserve the very freedom that they seek

to crush.  They are not satisfied merely with publishing programs having

limited capability, which free software permits. They seek to go further, to

prevent the user from removing those limits, turning Freedom 1, the freedom

to modify, into a sham.

GPLv2 did not address the use of technical measures to take back the rights

that the GPL granted, because such measures did not exist in 1991, and would

have been irrelevant to the forms in which software was then delivered to

users.  But GPLv3 must address these issues: free software is ever more

widely embedded in devices that impose technical limitations on the user's

freedom to change it.

These unjust measures must not be confused with legitimate applications that

give users control, as by enabling them to choose higher levels of system or

data security within their networks, or by allowing them to protect the

security of their communications using keys they can generate or copy to

other devices for sending or receiving messages.  These technologies present

no obstacles to the freedom of free software. The user is presented with

choices, and figuratively as well as literally retains all the keys to the

digital home.

By contrast, technical restrictions that allow other parties to control the

user have no legitimate social purpose.  In existing applications where the

user is not afforded the same degree of real power to modify the free

software in his system that vendors or distributors have retained, or have