In web development, the term backend refers to the server-side of a website or application that handles data storage, processing, and communication with clients. It includes the server, database, and application logic that work behind the scenes to deliver a seamless user experience. Backend technologies, such as programming languages like Java or Python, along with databases like MySQL or MongoDB, are essential for managing user requests, performing computations, and retrieving and storing data. The backend is crucial for ensuring that the frontend operates efficiently.