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<chapter id="getting-debian"><title>Getting and installing &debian;</title>
<para>
The official document giving installation instructions is the <ulink
url="&url-debian-installmanual;">Debian GNU/Linux
Installation Guide</ulink>.  We'll give some additional notes about getting and
installing &debian; here.
</para>
<section id="version"><title>What is the latest version of Debian?</title>
<para>
Currently there are three versions of &debian;:
</para>
<variablelist>
<varlistentry>
<term><emphasis>release &release;, a.k.a. the "stable" distribution or &releasename;</emphasis></term>
<listitem>
<para>
This is stable and well tested software, it changes if major security or
usability fixes are incorporated.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><emphasis>the "testing" distribution, currently called &nextreleasename;</emphasis></term>
<listitem>
<para>
This is where packages that will be released as the next "stable" are placed;
they've had some testing in unstable but they may not be completely fit for
release yet.  This distribution is updated more often than "stable", but not
more often than "unstable".
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><emphasis>the "unstable" distribution</emphasis></term>
<listitem>
<para>
This is the version currently under development; it is updated continuously.
You can retrieve packages from the "unstable" archive on any Debian mirror site
and use them to upgrade your system at any time, but you may not expect the
system to be as usable or as stable as before - that's why it's called
"<emphasis role="strong">unstable</emphasis>"!
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
Please see <xref linkend="dists"/> for more information.
</para>
</section>

<section id="updatestable"><title>Are there package upgrades in "stable"?</title>
<para>
Generally speaking, no new functionality is added to the stable release.  Once
a Debian version is released and tagged "stable" most packages will only get security
updates.  That is, packages for which a security vulnerability has been found
after the release will be upgraded.  All the security updates are served
through <ulink url="https://security.debian.org">security.debian.org</ulink>.
</para>
<para>
However, there are some cases in which packages will be updated in stable. For example:
</para>

<itemizedlist>

<listitem>
<para>When an urgent update is required to ensure the software continues working.</para>
</listitem>

<listitem>
<para>The package is a data package and the data must be updated in a timely manner.</para>
</listitem>

<listitem>
<para>The package needs to be current to useful to end user (e.g. some security software, such as anti-malware products).</para>
</listitem>

<listitem>
<para>The software is a leaf package and is broken by changes external to the distribution.</para>
</listitem>

</itemizedlist>

<para>
Users that wish to run updated versions of the software in stable have the
option to use "backports". Backports are recompiled packages from testing
(mostly) and unstable (in a few cases only, e.g. security updates), so they
will run without new libraries (wherever it is possible) on a stable Debian
distribution. Users can configure their system to use the backports repository
and download specific software. However, it is recommended to pick out single
backports which fit the specific needs, and not to use all backports available.
For more information read the <ulink
url="https://wiki.debian.org/DebianSoftware">Wiki entry describing software
available to Debian users</ulink> and
<ulink url="https://wiki.debian.org/Backports">Wiki entry on backports</ulink>.
</para>

<para>
Security updates serve one purpose: to supply a fix for a security
vulnerability.  They are not a method for sneaking additional changes into the
stable release without going through normal point release procedure.
Consequently, fixes for packages with security issues will not upgrade the
software.  The Debian Security Team will backport the necessary fixes to the
version of the software distributed in "stable" instead.
</para>
<para>
For more information related to security support please read the <ulink
url="https://www.debian.org/security/faq">Security FAQ</ulink> or the <ulink
url="https://www.debian.org/doc/manuals/securing-debian-howto/">Debian Security
Manual</ulink>.
</para>
</section>

<section id="inst-disks"><title>Where/how can I get the Debian installation images?</title>
<para>
Very likely, clicking the "Download" link on the <ulink
url="https://www.debian.org/">main page of the Debian website</ulink> will get
you what you need.  However, for more options, get the various installation
images from the <ulink url="https://www.debian.org/distrib/">Download
Debian</ulink> page.
</para>
<para>
Please refer to <ulink url="https://www.debian.org/CD">Debian GNU/Linux on
CDs</ulink> for more information about CD (and DVD) images.
</para>
</section>

<section id="cdrom"><title>How do I install Debian from CD-ROMs?</title>
<para>
Installing Debian from CD is straightforward: configure your system for booting
off a CD, insert your CD, and reboot.  Your system will now be running the
Debian Installer.  See the <ulink
url="&url-debian-installmanual;">Debian GNU/Linux
Installation Guide</ulink> for more information.
</para>
</section>

<section id="cdimage-symlinks"><title>Why does the official stable released CD-ROM contain symlinks for "frozen" and "unstable"? I thought this CD contains just "stable"!</title>
<para>
Official Debian CD images indeed contain symlinks like:
</para>
<screen>
 /dists/frozen -> &releasename;/
 /dists/stable -> &releasename;/
 /dists/testing -> &releasename;/
 /dists/unstable -> &releasename;/
</screen>
<para>
so that they work when your sources.list has an entry like
</para>
<screen>
 deb cdrom:[&lt;name as on cd label&gt;]/ unstable main [...]
</screen>
<para>
.
</para>
<para>
The fact these symlinks are present does <emphasis>not</emphasis> mean the
image is "unstable" or "testing" or anything.  Read the CD label in
<filename>/.disk/info</filename> to find out which Debian version it contains.
This information is also present in <filename>/README.txt</filename> on the CD.
</para>
<para>
Read <ulink url="&url-debian-releases;"/>
to find out what the current "stable" and "testing" releases are.
</para>
</section>

<section id="remoteinstall"><title>Can I get and install Debian directly from a remote Internet site?</title>
<para>
Yes.  You can boot the Debian installation system from a set of files you can
download from our archive site and its mirrors.
</para>
<para>
You can download a small CD image file, create a bootable CD from it, install
the basic system from it and the rest over the network.  For more information
please see <ulink url="https://www.debian.org/CD/netinst/"/>.
</para>
</section>

<section id="alternativebootinstaller"><title>Are there any alternative strategies for booting the system installer?</title>
<para>
Yes.  Apart from CD or DVD, you can install &debian; by booting from
USB memory stick, directly from hard disk, or using TFTP net booting.  For
installing on multiple computers it's possible to do fully automatic
installations.  NB: not all methods are supported by all computer
architectures.  Once the installer has booted, the rest of the system can be
downloaded over the network, or installed from local media.  See the <ulink
url="&url-debian-installmanual;">Debian GNU/Linux
Installation Guide</ulink> for more information.
</para>
</section>

</chapter>