A cellular automaton (CA) is a collection of cells arranged in a grid, such that each cell changes state as a function of time according to a defined set of rules that includes the states of neighboring cells. Cellular automata have been suggested for possible use in public key cryptography.
Common cell shapes are squares, hexagons, and cubes. The simplest cellular automata are one-dimensional, with cells on a straight line, where each cell can have only two possible states (such as high/low or black/white). But in theory, a CA can have any number of dimensions, and each cell can have any number of possible states. The state of each cell changes in discrete steps at regular time intervals. The state of a cell at any given time depends on two things: (1) its own state in the previous time step, and (2) the states of its immediate neighbors in the previous time step. When a graphical rendition of a CA is viewed, it looks like a "quantized" animated object.
Cellular automata have been used to study the evolution of disease epidemics by means of computer modeling. Cellular automata occur in various natural systems and processes and can be illustrated by the pigmentation that occurs when sea shells form. Plant respiration also occurs according to a CA process, with each stomata on a leaf playing the role of an individual cell.