Backend as a Service (BaaS) is a cloud service model that enables developers to outsource the backend components of web or mobile applications. It encompasses essential functionalities such as server management, database management, authentication, push notifications, and cloud storage, allowing developers to concentrate on frontend development while the service provider handles the backend infrastructure. This model is particularly advantageous for developers and businesses aiming to accelerate development timelines and reduce the complexity of managing backend systems, ultimately fostering more efficient application creation and deployment.