Fractals is a hands-on introduction to the visualization of mathematical objects, algorithms and data. The book gives a self-contained introduction to J as raster and object graphics are introduced. Fractal times series illustrate techniques for dealing with one-dimensional data. Studies of iterated function systems and chaotic attractors offer experience with visualizing two dimensional phenomena while investigating fractals and symmetry. Finite automata and fast Fourier transforms are used for playful things like the game of life and serious topics such as image processing. Similar techniques are used for studying classical complex dynamics illustrated by the Mandelbrot set and Julia sets. The mathematics of three dimensional projection is discussed and visualization of three dimensional data is the focus of scenes created by rendering J created objects with raytracers and OpenGL.