Mandelbrot and Julia sets. There are several options apart from zooming. Draw a Julia set for any position on the Mandelbrot image. Set a path on the Mandelbrot image and then see an animation of Julia sets along the path. There is a page explaining various aspects.

New version 24.4.21 adds several new features including additional polynomial terms inspired by a post in r/fractals on Reddit. More details in the explanatory notes when you run the program.