A Backend Developer designs, implements and maintains the server-side of web applications. They handle data storage solutions, create server-side logic, integrate front-end components, and develop APIs. They work with programming languages like Java, Python, or Ruby, and tools like MySQL, Oracle, and SQL Server to store and organize data. They ensure the server, application, and database communicate with each other seamlessly, implementing security and data protection measures. They also troubleshoot and debug applications, upgrade and make necessary modifications, and collaborate with front-end developers to integrate user-facing elements with server-side logic.