Summary  
This chapter explains how to manage asynchronous operations by handling their loading, success, and error states.  

General domain of usage  
Data fetching from external services


In this section, you will work with data that comes from outside your application.





## The Difference

So far, all state changes happened instantly.
When you work with APIs, things are different. Data takes time to load, can fail, and does not always behave predictably.





## What Changes

When you fetch data, you now deal with multiple states:
* Loading while the request is in progress;
* Success when the data is received;
* Error when something goes wrong.






Your application must handle all these states correctly.
Without proper handling, users may see empty screens, outdated data, or no feedback at all.


Learn how to manage complex application state in React using Redux Toolkit. Understand when Redux is actually needed, build state with slices, handle async data, and connect everything into a predictable flow. 

Understand why Redux Toolkit exists and when it becomes useful. Recognize how state complexity grows in real applications and why simple approaches stop scaling.

Install Redux Toolkit and set up the store. Connect Redux to a React application and understand how data flows through the system.

Define state using slices and organize logic clearly. Create reducers, use generated actions, and keep state manageable as the application grows.

Read data from the store using useSelector and update it with useDispatch. Structure state correctly and avoid common mistakes when working with shared data.

Fetch data from APIs using createAsyncThunk. Manage loading and error states and keep the UI in sync with async updates.

Split state into multiple slices and organize files by feature. Combine reducers cleanly and maintain a clear structure as the application grows.

Build a complete application using Redux Toolkit. Implement CRUD features, handle async data, and improve the user experience with loading and error states.

Why Async Logic Is Different

The Difference

What Changes