Overview
A state machine allows for a controlled change from one state to another. It sets up a well-defined set of possible states and what transitions are possible between them. It’s up to you to ‘drive’ the machine, telling it when to transition.
Why?
Behaving according to a current state is a common pattern in programming interactivity. This is often solved by using different variables track state. A downside is that you have to be mindful what variables or conditions alter state as well as when and where to enforce rules about state changes.
A state machine therefore can help you catch errors and makes coding simpler when you know there are a fixed number of well-defined states to handle, and they are only activated according to a logic you have defined.