Loadable Kernel Module (LKM) is a software program that allows inserting or removing new features, functionalities or device drivers into a running operating system kernel without the need to reboot the system. It is a specialized skill that requires knowledge in operating systems, programming languages such as C, and Linux kernel APIs. LKM enables developers to add or remove specific functionalities or drivers to the kernel without modifying the entire system, making the process faster and more efficient.