RxSwift is a reactive programming library for Swift, designed to simplify asynchronous programming and event-driven code. It allows developers to work with streams of data, making it easier to manage complex user interactions and asynchronous tasks in iOS applications. By using RxSwift, developers can create a more responsive user interface and handle events like button taps or network responses in a more organized way. The library promotes a declarative approach, enabling developers to express their intentions clearly and manage state changes efficiently through observable sequences.