alive, stays alivealive, dies nextempty, is born next
The four rules, applied to every cell at once
A live cell with fewer than 2 live neighbours dies — it is too lonely.
A live cell with 2 or 3 live neighbours stays alive.
A live cell with more than 3 live neighbours dies — it is overcrowded.
An empty cell with exactly 3 live neighbours comes to life.
Every cell has eight neighbours: across, up, down and diagonally. The board wraps around — a cell on the right edge is a neighbour of the cell opposite it on the left edge, and the top edge touches the bottom — so nothing ever falls off.