B3/S23 is the whole rulebook
Conway's Game of Life runs on a square grid where every cell is either alive or dead. Each cell checks the eight cells around it. A dead cell is born when exactly three neighbors are alive. A live cell survives with two or three live neighbors. With fewer than two it dies from isolation; with more than three it dies from crowding.
That rule is often written as B3/S23: births on 3, survival on 2 or 3. There is no score, no player turn, and no hidden random event after the starting pattern is chosen.
Slow rule demo
Watch B3/S23 change a blinker one tick at a time
The dark cells are alive now. Green marks cells that will be born on the next tick, and red outlines mark live cells that will die. The useful detail is that all of those changes happen together.
Everything changes at once
The easy mistake is to update cells one by one. Life does not work that way. The next generation is computed from the current generation, then all births and deaths are applied together in a single tick.
This is why the blinker works as a clean first lesson. In one tick, the vertical row creates two side births and loses its two endpoints. In the next tick, the same logic reverses the shape.
What to run after B3/S23
If you searched for B3/S23, the next useful move is not another definition. Run a blinker for two ticks, a pulsar for three, and the R-pentomino for the first few generations. The same rule explains all three, but the behavior on the board changes fast.
The Gosper glider gun is the larger test. It still follows B3/S23, yet its core repeats every 30 generations and releases a glider. That gap between a short rule string and a working emitter is why Life is worth running, not just reading.
Simple does not mean tame
The rules are short, but the board is not easy to predict. The same rule set supports still lifes that never move, oscillators that repeat, spaceships that translate, methuselahs that run for thousands of generations, and guns that emit endless streams of gliders.
That is the practical reason this site treats Life as a research topic rather than a toy grid. The right question is not only what the rule says. It is what a pattern does when the rule is applied without shortcuts.
Working takeaway
When a pattern looks surprising, slow the simulator down and ask which cells had exactly three neighbors, and which live cells kept two or three. Most Life explanations start there.
Fast answers
Common search questions
What does B3/S23 mean in Conway's Game of Life?
B3 means a dead cell is born with exactly three live neighbors. S23 means a live cell survives with two or three live neighbors. All cells update at the same time.
Which pattern should I run first after learning the rules?
Use the blinker first because it shows simultaneous updates in two ticks. Then run a pulsar for period 3, R-pentomino for a long transient, and the Gosper gun for repeated glider output.