Turtle graphics is a style of computer drawing based on preserved state (position and orientation) and a small number of operations against that state (forward, turn, pen up & down). SeymourPapert promoted (invented?) turtle graphics and the associated turtle geometry as a simplification that made computers and algorithmic thought accessible to kids. The state was called the ''turtle'' and programs taught the turtle how to draw.

See LogoLanguage.

----
  to draw-a-box 
	forward 10
	turn 90
	forward 10
	turn 90
	forward 10
	turn 90
	forward 10
	turn 90

  to draw-a-window
	draw-a-box
	turn 90
	draw-a-box
	turn 90
	draw-a-box
	turn 90
	draw-a-box
	turn 90
http://c2.com/wiki/turtle.gif

-----

A Lindenmayer System is a 3-dimensional turtle graphics system tuned to draw fractals. FractalLifeEngine is an example of one:

http://flea.sourceforge.net/fast_example.png.

http://flea.sourceforge.net