GNU/Linux
GNU/Linux is a free and open-source operating system that combines the GNU userland tools with the Linux kernel. It provides a Unix-like environment for running applications, managing hardware, and performing system tasks, widely used in servers, desktops, and embedded systems. The system emphasizes modularity, security, and customization, with numerous distributions (distros) tailored for different use cases.
Developers should learn GNU/Linux for server administration, cloud computing, and DevOps, as it powers most web servers and cloud infrastructure. It's essential for system programming, scripting, and working with open-source tools, offering deep control over the environment and compatibility with development frameworks like Docker and Kubernetes.