Redux is a state management library for JavaScript applications, commonly used with React. The main components involved in Redux are:
1. **Store**: Holds the application's state.
2. **Actions**: Plain JavaScript objects that describe changes to the state.
3. **Reducers**: Functions that specify how the state changes in response to actions.
4. **Middleware**: Functions that extend Redux's capabilities, allowing for side effects like asynchronous actions.
Redux is a predictable state container for JavaScript apps based on the Flux design pattern. Redux can be used together with React, or with any other view library. It is tiny (about 2kB) and has no dependencies.