Translations by Joel Goguen

To enable Synaptic and other package managers to install software from CDs which contain packages:

The packages should then be listed. To have Synaptic only list packages from the CD, click the <guibutton>Origin</guibutton> button on the lower left corner of the Synaptic window and then find the name of the CD in the list in the upper left corner the window.

Further documentation on APTonCD can be found on its website, <ulink url="http://aptoncd.sourceforge.net"> aptoncd.sourceforge.net</ulink>

Most of the software available for Ubuntu is free, open-source software. This software is free for anyone to install and use, and people can modify the software and redistribute it if they like. Ubuntu is built from this type of software.

<emphasis role="strong">Non-free software</emphasis> is software which is not freely redistributable or modifiable. This makes it difficult for the Ubuntu developers to improve the software and correct problems, so it is normally recommended that you use <ulink url="http://www.ubuntu.com/ubuntu/philosophy"> free software</ulink> instead.

<emphasis role="strong">Restricted software</emphasis> is software which has restrictions on its use, preventing it from being classed as free software. Non-free software is a type of restricted software, where the restrictions are due to the software having a non-free license. Other reasons for software being classed as restricted include legal issues (use of some types of software is illegal in some countries) and patent issues (some software requires a patent license to be used legally).

You should be warned by the package manager when you try to install restricted software. If the restricted software cannot be used legally in your country then there is little you can do; you should not install the software. If the software is restricted simply because it is non-free, you may choose to use it (for example, in the case of graphics card drivers). Be aware that most restricted software is not supported in Ubuntu, and problems with such software often cannot be corrected by Ubuntu developers.

Sometimes it is difficult to determine why a particular software package is restricted. If this is the case, seek advice on the <ulink url="http://ubuntuforums.org/">Ubuntu Forums</ulink>. If you are still unable to determine why a package is restricted, err on the side of caution and do not install it; it may be illegal to use it in your country.

When you install software on Ubuntu, the package manager automatically downloads the required software packages from a <emphasis>software repository</emphasis>, a location on the Internet which stores collections of packages ready to be downloaded.

There are thousands of programs available to install on Ubuntu. These programs are stored in software repositories and are made freely available for all Ubuntu users. This makes it very easy to install new programs, and it is also very secure because each program you install is built specially for Ubuntu and checked before it is allowed into the repositories.

The Update Manager automatically finds software updates for your computer when they are available. It regularly gathers information on potential updates from a number of online update sources.

If you click <menuchoice><guimenu>System</guimenu><guimenuitem>Administration</guimenuitem><guimenuitem>Software Sources</guimenuitem></menuchoice> and select the <guilabel>Updates</guilabel> tab, you will notice that four update sources are available. An explanation for each of these is provided below:

<emphasis role="strong">Important security updates:</emphasis> Updates which fix critical security flaws are made available through this source. It is recommended that all users leave this source enabled (it should be enabled by default).

<emphasis role="strong">Recommended updates:</emphasis> Updates which fix serious software problems (which are not security flaws) are made available through this source. Most users will want to leave this source enabled as common and annoying problems are often fixed with these updates.

<emphasis role="strong">Unsupported updates:</emphasis> When new versions of popular software are released they are sometimes <quote>back-ported</quote> to an older version of Ubuntu so that users can benefit from new features and fixes for problems. These backports are unsupported, may cause problems when installed and should only be used by people who are in desperate need of a new version of a software package which they know has been backported.