Final answer:
Redux stores data in a single JavaScript object called the 'store,' which centralizes the state of an application and facilitates predictable state management.
Step-by-step explanation:
The question pertains to Redux, which is a state management library often used with JavaScript applications, most notably with React. In Redux, the data is stored in a single JavaScript object referred to as the store. The store is created by using the Redux function createStore() and is the central location for all the state of an application. The data in the store is made immutable, meaning it cannot be changed directly. Instead, to update data, an action is dispatched which describes what change needs to happen, and then a reducer function specifies how the state changes in response to that action. The importance of the store lies in its ability to centralize the application's state, making it easier to keep track of state changes and provides a predictable state management flow.