Life occurs on a virtual checkerboard. The squares are called cells.
They are in one of two states: alive or dead. Each cell has eight possible neighbors, the cell whichs touch its sides or its corners.
It will die of overcrowding if there are more than three live neighbors, and it will die of exposure if there are fewer than two.
If a cell on the checkberboard is dead, it will remain dead in the next generation unless exactly three of its eight neighbors are alive. In that case, the cell will be "born" in the next generation.