When working with Redux in a React application, several key components and concepts are essential to ensure efficient state management. Here are the main components to consider:

1. Store: The single source of truth in a Redux application. It holds the entire state of the application and is created using the createStore function. The store can be accessed using getState(), and updates can be dispatched to it.

2. Actions: Plain JavaScript objects that represent an intention to change the state. Actions must have a type property, and they may also include a payload with additional information. Actions are dispatched to the store using the dispatch method.

3. Action Creators: Functions that create and return action objects. They encapsulate the action creation process, making it easier to manage and dispatch actions.

4. Reducers: Pure functions that take the current state and an action as arguments and return a new state. Reducers determine how the state changes in response to actions. They must not mutate the state directly; instead, they should create and return new state objects.

5. Middleware: Enhancements for the Redux store that allow you to add additional functionality, such as logging actions, handling asynchronous actions (e.g., using redux-thunk or redux-saga), or other custom behavior. Middleware can intercept actions and perform operations before they reach the reducer.

6. Selectors: Functions that extract and derive data from the state. Selectors help encapsulate the logic for accessing specific pieces of state and can improve performance through memoization.

7. Provider: A component that wraps the main application, making the Redux store available to all nested components through the context API. It is provided by the react-redux library using the component.

8. Connect: A higher-order function from react-redux that connects React components to the Redux store. It maps state and dispatch to the component's props, allowing the component to access the store's state and dispatch actions.

9. useSelector and useDispatch Hooks: Hooks provided by react-redux that allow functional components to access the Redux store. useSelector allows components to read data from the store, while useDispatch provides a way to dispatch actions.

10. Immutability: Ensuring that state updates are done immutably is crucial in Redux. Using libraries like Immer can simplify the process of handling immutability in reducers.

By focusing on these components, you can build a well-structured and maintainable state management solution in your React applications using Redux.