Bacon.js is a functional reactive programming (FRP) library for JavaScript. It allows developers to build complex applications by composing event streams and property streams. This enables elegant handling of asynchronous events, user interactions, and data updates. Bacon.js promotes a declarative style of coding, enhancing code readability and maintainability. Crucially, it simplifies complex event handling scenarios, leading to more robust and testable applications, often used with web frameworks.