A row of black and white cells; each cell looks at its two neighbours and a rule says what it becomes in the next row. There are 256 such rules. Most freeze or dissolve into noise within a few steps. Rule 110 breeds structures that live, travel and collide, and in 2004 Matthew Cook proved it can compute anything a computer can. That narrow regime between order and chaos is what complexity science calls the edge of chaos.
Flip the bits of the rule, drop cells into the field, or pick any of the 256 rules below.