On many older computers, the console is an RS-232 link to a terminal such as a DEC VT100. This terminal is in a locked room and is continually observed by the minicomputer's operators. Large systems from Sun, Hewlett-Packard and IBM still use serial consoles.
It is usually possible to login from the console. A login session from the console is treated by many parts of the operating system as being more trustworthy than a login session from other sources. Logging in as the root super-user from the console is the Command Line of Last Resort when faced with a misbehaving system.
See also: for graphic (no-text) window see XFree86.