Conway's Game of Life is played on an infinite two-dimensional board. The state of a cell is
either alive or dead. The world can be initialized in any way, but from the initial
generation, the world continues
one generation at a time, each generation dependent only on the previous generation. In fact, the
state of a cell in generation g + 1 depends only on the state of the 9 cells around that cell
in generation g. If a cell is alive in generation g, and it has 2 or 3 living neighbors,
or if it is dead, and it has exactly 3 living neighbors, it will be alive in generation g + 1,
otherwise it will be dead. This game was invented by John Horton Conway in 1970.

Below you can play a modified version of the game.
Instead of being infinite, this board is 30 by 30 and the topology is like a donut;
the top row is adjacent to the bottom and the left column is adjacent to the right.
You can initialize the world randomly or in a line or in a square and you can
toggle the state of a cell by clicking on it.

In July of 2007 I looked into creating animated GIFs and here's the result.
Here are some common Game of Life constellations:
block
blinker
tub
beehive
loaf
glider
boat
long boat
ship
pond
canoe
pulsar

For each of the following links I started with a cross where the four line segements have the same lengths. The following numbers indicate these lengths.

11 This is the simplest start of this form which leads to a final population greater than twelve.

15 This is the simplest start of this form which generates gliders that continue forever.

33 This scenario takes much longer to stabalize than all starting configurations with shorter lengths.

34 This scenario stablizes with a greater variety of constellations.

78 This is the simplest start of this form that stabalizes with pulsars. It also has several colliding gliders.
(warning: this gif has a 2.6 megabyte size)