A commonly used programming language for back-end development is Java. Known for its portability, robustness, and scalability, Java is widely utilized for building server-side applications, web services, and enterprise-level systems. Its extensive ecosystem includes frameworks like Spring and Hibernate, which simplify development tasks. Furthermore, Java's ability to handle concurrent processing and large data volumes makes it suitable for high-performance applications. The language's strong community support and rich libraries contribute to its popularity in back-end development.