A pattern that repeatedly creates gliders, and thus grows without bound. Was the first infinitely-growing pattern to be found. Discovered in 1970. More info on LifeWiki
Conway's Game of Life is a cellular automaton that is played on a 2D square grid. Each square (or "cell") on the grid can be either alive or dead, and they evolve according to the following rules:
Any live cell with fewer than two live neighbours dies (referred to as underpopulation).
Any live cell with more than three live neighbours dies (referred to as overpopulation).
Any live cell with two or three live neighbours lives, unchanged, to the next generation.
Any dead cell with exactly three live neighbours comes to life.
The initial configuration of cells can be created by a human, but all generations thereafter are completely determined by the above rules. The goal of the game is to find patterns that evolve in interesting ways – something that people have now been doing for over 50 years.
The best way to first learn about the game is to play it, either via the LifeViewer above, or by downloading the Life simulation program Golly. Draw some patterns and then press the "Play" button to see how they evolve. Once you have gotten comfortable with the game, you can have a look at LifeWiki or Catagolue to browse what is known about it, or you can read the book for a more directed guide to the world of Life.