This is the 124th iteration of a "neighbour counting" cellular automaton. Each cell can be in one of two states, "on" or "off." The behaviour of each cell at iteration N+1 is defined by the number of neighbours in the 'on' state it has and whether the cell in question is on or off. An "on" cell with three or more "on" neighbours goes to "off", otherwise it stays "on." If a cell is "off" and has 1 or 2 neighbours switched "on", it swtiches "on." If it has three or more "on" neighbours, it stays "off." If it has zero neighbours "on", it remains "off." See the animated version below.