(During this time you will probably see a logo of your computer manufacturer.) Note: UEFI fast boot may be too fast to give time to press any key. If booting into recovery mode does not work you can still use your installation CD (if it is a live cd) as described in LivecdRecovery. You are then logged in as root (the superuser) and can repair your system using command line tools. This mode just loads some basic services and drops you into command line mode.
If your system fails to boot for whatever reason, it may be useful to boot it into recovery mode.
