Flux is an architecture for building JavaScript applications that promotes unidirectional data flow. The key elements of Flux are the Dispatcher, Stores, and Views. The Dispatcher centralizes the flow of data and dispatches actions to the Stores. Stores contain application state and logic. Views are React components that subscribe to Stores and listen for changes to re-render. Actions define activities and are dispatched by action creators through the Dispatcher to the Stores to update state.