A console or terminal emulator is a command line interface to a shell. You can use it to call shell commands and start programs by using your keyboard only. The console typically prints a prompt and expects you to enter your commands behind it. Here is an example:
bort:/boot # ls initrd* initrd initrd-22.214.171.124-0.1-default initrd-126.96.36.199-0.1-xen initrd-xen bort:/boot # firefox
To use a console, press ALT_F2 and input the name of a console program as listed below.
Open a console
See open a console.