The kernel is the core component of an operating system (OS) that manages system resources and facilitates communication between hardware and software. It operates at the lowest level of the system architecture, directly interacting with the hardware, including the CPU, memory, and input/output devices, while providing essential services to user applications.

The kernel is responsible for key tasks such as memory management, process scheduling, device drivers, and file system management. It ensures that each application has access to necessary resources while preventing interference between applications. Kernels can be broadly classified into monolithic kernels and microkernels. A monolithic kernel (like in Linux) includes all core functionalities in a single large block of code, whereas a microkernel only includes the most essential components and runs additional services in user space, improving modularity.

Modern operating systems, including Windows, macOS, Linux, and Android, rely on kernels to abstract hardware complexities, ensuring that applications can function without needing direct access to hardware resources. The kernel ensures stability and security by enforcing process isolation and controlling access to system resources.