"The whole is more than the sum of its parts." While this phrase is well-known as a platitude, its influence on the worldview of our modern science is both new and powerful. Atoms, molecules, cells, and organisms create the structural richness of our world through simple interactions. A crucial tool for understanding this complexity is computer simulations, which allow researchers to artificially approach reality. Cellular automata are such simulation models. In them, the world becomes a digital universe—a network of the simplest interconnected digital computers that generate complex macroscopic structures with the simplest programs. This book guides you through the digital cosmos and illustrates the strengths and weaknesses of these simulation tools with numerous examples. However, it also exposes you to the irresistible.