The state of your application is stored in an object tree within a single store. (In contrast with vanilla React where app state is held inside of a React component, or across multiple components.)
Actions are JavaScript objects that describe changes that you want to make to your application state.
You send them to the store using the dispatch
function.
Reducers specify how the application's state changes in response to actions. A reducer is a function that takes the existing state and an action, and returns a new state.