When you use Zustand for state management in React, you work with three core ideas: stores, actions, and state slices. A store in Zustand is a centralized object that holds all the state your application or a part of your application needs. It acts as the single source of truth, allowing you to read and update state from anywhere in your component tree.

Actions are functions defined inside the store that let you modify the state. Instead of directly changing values, you call these actions to update the store. This approach keeps your state logic organized and predictable.

To keep your state manageable, you can divide it into state slices. A state slice is simply a logical grouping of related state and actions. For example, you might have a user slice for authentication data and a cart slice for shopping cart items. Each slice is responsible for its own part of the state, but all slices live together in the same store, making it easy to scale your app's state as it grows.

Zustand is designed with three principles in mind: immutability, simplicity, and performance. Immutability means that when you update state, you produce a new version of it instead of modifying the old one. This makes it easier to track changes and avoid bugs.

Simplicity is at the heart of Zustand's API. You define your store with plain JavaScript objects and functions—no complex boilerplate or hidden magic. This makes your codebase easier to understand and maintain.

Finally, performance is a key advantage of Zustand. It uses shallow comparison and only re-renders components that actually use the part of the state that changed. This means your app stays fast, even as your state grows more complex.