Kernel#

The kernel is a computer program at the core of a computer’s operating system and generally has complete control over everything in the system.

https://en.wikipedia.org/wiki/Kernel_(operating_system)

Loadable kernel module#

https://en.wikipedia.org/wiki/Loadable_kernel_module

Kernel and User Modes#

Kernel mode allows full access to devices and the execution of privileges instructions. User mode request privileges operations to kernel via system calls.

Switching between user and kernel modes is a mode switch.

https://en.wikipedia.org/wiki/User_space_and_kernel_space