great introduction guide to Redux:

Redux is a predictable state container for JavaScript apps. It's an application data-flow architecture, rather than a traditional library or a framework like Underscore.js and AngularJS. It is used mostly for application state management. To summarize it, Redux maintains the state of an entire application in a single immutable state tree (object), which can’t be changed directly. When something changes, a new object is created (using actions and reducers). Today, Alex Bachuk will go over the core concepts in detail.