Linux, a free and open-source operating system, is the dominant OS on servers but less popular on personal computers. It traces its roots back to Unix and interacts with hardware via its kernel, written in C. The kernel manages processes, memory, and file systems. Understanding Linux involves recognizing commands, file permissions, and different distributions. Shells like Bash facilitate user interaction with the system. Linux allows for extensive customization via scripts and environment variables, making it essential knowledge for developers.