kernel
also: Linux kernel, OS kernel
The core component of Linux that manages hardware resources, schedules processes, and handles system calls from user applications.
The kernel is the lowest-level software layer that sits between applications and hardware. It abstracts away hardware complexity and enforces security by mediating all direct hardware access through controlled interfaces.
Key responsibilities include: process scheduling (deciding which processes run and when), memory management (allocating RAM), interrupt handling (responding to hardware signals), and device drivers (communicating with hardware like disks and network cards).
When you run a command like ls, the application requests data from the kernel via a system call. The kernel then interacts directly with your disk hardware, retrieves the data, and returns it to the application.
You can check your running kernel version with uname -r, which typically shows something like 5.15.0-84-generic. The kernel is loaded into memory at boot time by the bootloader.