6.7 What is an Essential Required, Important, Standard, Optional, or Extra package?

Each Debian package is assigned a priority by the distribution maintainers, as an aid to the package management system. The priorities are:

• Required: packages that are necessary for the proper functioning of the system.

  This includes all tools that are necessary to repair system defects. You must not remove these packages or your system may become totally broken and you may probably not even be able to use dpkg to put things back. Systems with only the Required packages are probably unusable, but they do have enough functionality to allow the sysadmin to boot and install more software.

• Important packages should be found on any Unix-like system.

  Other packages which the system will not run well or be usable without will be here. This does NOT include Emacs or X11 or TeX or any other large applications. These packages only constitute the bare infrastructure.

• Standard packages are standard on any Linux system, including a reasonably small but not too limited character-mode system.

  This is what will install by default if users do not select anything else. It does not include many large applications, but it does include some development software like the GNU C and C++ compilers (gcc, g++), GNU make, as well as the Python interpreter and some server software like OpenSSH, the BSD printer daemon (lpr) and the RPC portmapper (portmap).

• Optional packages include all those that you might reasonably want to install if you did not know what it was, or do not have specialized requirements.

  This includes X11, a full TeX distribution, and lots of applications.

• Extra: packages that either conflict with others with higher priorities, are only likely to be useful if you already know what they are, or have specialized requirements that make them unsuitable for "Optional".

If you do a default Debian installation all the packages of priority Standard or higher will be installed in your system. If you select pre-defined tasks you will get lower priority packages too.

Additionally, some packages are marked as Essential since they are absolutely necessary for the proper functioning of the system. The package management tools will refuse to remove these.