loadable module
also: kernel module, LKM (Loadable Kernel Module)
A piece of kernel code that can be dynamically loaded into or unloaded from a running Linux kernel without recompiling or rebooting the system.
Loadable modules (also called kernel modules) are object files containing kernel code that extend the Linux kernel's functionality at runtime. Instead of rebuilding and rebooting the entire kernel, you can compile a module separately and insert it into a running kernel using the insmod or modprobe commands.
Common uses include device drivers for hardware like network cards, sound devices, or USB controllers, as well as filesystem support and specialized functionality. For example, loading the e1000 network driver: modprobe e1000 immediately makes that hardware available without a reboot.
Modules live in /lib/modules/$(uname -r)/kernel/ organized by category. You can list loaded modules with lsmod, remove them with rmmod, and view their parameters with modinfo. Modern systems typically autoload necessary modules at boot through udev and initramfs.