From my history-book:

VT52 and VT100 are terminal-types. Those are things with a VDU and keyboard and usually have a serial port. The cursor on the screen (80 chars wide by 25 lines high, no graphics) was (is) controlled by means of a string of chars sent to the device usually preceded by an ESC (escape) char. Hence the name escape-sequence..

Oh yes before you ask: VDU = Video Display Unit

and

http://www.columbia.edu/acis/history/vt100.html

But all of the above can easily be found through through google.

regards