Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Rule 90 is a one-dimensional binary cellular automaton. The Sierpinski triangle (also with the original orthography Sierpi ski), also called the Sierpinski gasket or the Sierpinski Sieve, is a fractal named after the Polish mathematician Wac aw Sierpi ski who described it in 1915. Originally constructed as a curve, this is one of the basic examples of self-similar sets, i.e. it is a mathematically generated pattern that can be reproducible at any magnification or reduction. Comparing the Sierpinski triangle or the Sierpinski carpet to equivalent repetitive tiling arrangements, it is evident that similar structures can be built into any rep-tile arrangements.