Shows the list of components to the user during installer operation, and starts a component when it is selected. Main-menu's questions are set to priority medium, so if your priority is set to high or critical (high is the default), you will not see the menu. On the other hand, if there is an error which requires your intervention, the question priority may be downgraded temporarily to allow you to resolve the problem, and in that case the menu may appear.

You can get to the main menu by selecting the Go Back button repeatedly to back all the way out of the currently running component.

Allows the user to select localization options for the installation and the installed system: language, country and locales. The installer will display messages in the selected language, unless the translation for that language is not complete in which case some messages may be shown in English.

Shows a list of keyboards, from which the user chooses the model which matches his own.

Automatically detects most of the system's hardware, including network cards, disk drives, and PCMCIA.

Looks for and mounts an Ubuntu installation CD.

Configures the computer's network connections so it can communicate over the internet.

Searches for ISO images (.iso files) on hard drives.

Presents a list of Ubuntu archive mirrors. The user may choose the source of his installation packages.

Checks integrity of a CD-ROM. This way, the user may assure him/herself that the installation CD-ROM was not corrupted.

Lowmem tries to detect systems with low memory and then does various tricks to remove unnecessary parts of debian-installer from the memory (at the cost of some features).

Anna's Not Nearly APT. Installs packages which have been retrieved from the chosen mirror or CD.

Updates the system clock and determines whether the clock is set to UTC or not.

Selects the time zone, based on the location selected earlier.

Allows the user to partition disks attached to the system, create file systems on the selected partitions, and attach them to the mountpoints. Included are also interesting features like a fully automatic mode or LVM support. This is the preferred partitioning tool in Ubuntu.

Helps the user with the configuration of the LVM (Logical Volume Manager).

Allows the user to set up Software RAID (Redundant Array of Inexpensive Disks). This Software RAID is usually superior to the cheap IDE (pseudo hardware) RAID controllers found on newer motherboards.

Installs the most basic set of packages which would allow the computer to operate under Linux when rebooted.

Sets up the root password, and adds a non-root user.

Configures apt, mostly automatically, based on what media the installer is running from.

Uses tasksel to select and install additional software.

Detects currently installed operating systems on the computer and passes this information to the bootloader-installer, which may offer you an ability to add discovered operating systems to the bootloader's start menu. This way the user could easily choose at the boot time which operating system to start.

The various bootloader installers each install a boot loader program on the hard disk, which is necessary for the computer to start up using Linux without using a floppy or CD-ROM. Many boot loaders allow the user to choose an alternate operating system each time the computer boots.

Allows the user to execute a shell from the menu, or in the second console.

Provides a way for the user to record information on a floppy disk, network, hard disk, or other media when trouble is encountered, in order to accurately report installer software problems to Ubuntu developers later.