Finite State Machines are a model of computation that obey the following rules:

- FSMs are always in one of a finite number of states.
- A FSM might go from one state to another based on an input
- this is called a
*state transition* - the input might be called an
*event*or*action*

- this is called a
- A FSM has an initial state

## State Transitions Stochasticity

State transitions can be stochastic as in nondeterministic finite automaton. This means that there’s a probability that, given an action, a state transition from `s`

to `s'`

will happen.