Fractal
A fractal is defined as a figure that does not become simpler under any level of magnification.
Mandelbrot set
Probably the most well-known example of a fractal, the Mandelbrot set is the set of all points in the complex plane for which the sequence is bounded.
This fractal is NOT self-similar. However, it is almost self-similar. If one were to plot all points in the Mandelbrot set using the complex plane, it would look like this.