- A connected network of cells (usually 2D), i.e.
**discrete**space

- Time is discrete as well

**Interactions are strictly local**

- Each cell can be in one of a number of pre-defined
**states**

- At each time-step, the new state of a cell is determined
from its existing state and the states of its
**neighbours,**via an explicit mapping (the**transition function**or**rule table**)

- Some variations (non-uniform rules, asynchronous updates, etc.)