Backend Development refers to the server-side logic and infrastructure that powers a web or mobile application behind the scenes. It involves working with databases, servers, APIs, and application logic to ensure data is processed, stored, and delivered efficiently. Backend developers use languages like Node.js, Python, PHP, Java, and frameworks such as Express, Django, Laravel, or Spring to build robust and scalable systems. They also manage authentication, security, server configuration, and performance optimization. A well-structured backend ensures the application runs smoothly, supports the front-end interface, and provides a secure and reliable experience for users.