A Backend Developer is a type of software engineer who focuses on the server side of web applications. They are responsible for creating and maintaining the logic, database interactions, and server configuration that power the application. Their work ensures that the front end, which users interact with, functions smoothly and efficiently. Backend Developers typically use programming languages like Python, Java, or Ruby to build the server-side components. They also work with databases such as MySQL or MongoDB to store and retrieve data. Their role is crucial for ensuring that applications are secure, scalable, and perform well under various conditions.