Today’s advent calendar post deals with Cellular Automata.
What are cellular automata? I’m glad you asked! They are systems made up of only a few parts: A kind of field or “world” made up of cells, a set of states that every cell can be in at any point, a “neighborhood” describing what cells are visible to each cell, and a set of rules governing what a cell will change its state into given its own state and the state of all cells in its neighborhood.
That is, of course, a very abstract description, so let me give a few examples for the individual parts to hopefully give you an idea of what you might see in a cellular automaton:
In typical worlds you might find cells arranged like beads on a string, or like fields on a chess or chinese checkers board. There are also more exotic configurations you can make up: Any 2-dimensional field can be mapped onto any surface, like for example the Stanford bunny.