Before we get any further into the mechanics of the installation, there is one useful feature you should know about. If you're doing a graphical install, you're actually on what is referred to as virtual console seven, equivalent to the seventh console which supports a login session. So why do you care?
As the installation progresses, you have the ability to switch back to one of the lower-numbered virtual consoles to see what's going on in the background, perhaps to read kernel messages or even run a few simple commands.
To switch to one of these lower consoles, simply type the key sequence Ctrl+Alt+Fn. Initially, the first four virtual consoles (one through four) represent, respectively, the installation dialog, a shell prompt, the install log and kernel-generated system messages. (The fifth console becomes active only later in the installation). The information displayed on these consoles can tell you things like the drivers that the kernel had loaded, hardware that was (or was not) detected, the amount of memory detected, and so on.
In order to switch away from the graphical install console, you need to type the full key sequence Ctrl+Alt+Fn. However, to move between the command-line consoles or back to the graphical console, you may, if you want, use the shorter key sequence Alt+Fn, although the longer sequence will still work.