A microkernel is a minimalistic approach to operating system design that focuses on providing only the essential services needed for the system to function. This includes basic functions like communication between processes and managing memory. By keeping the core of the operating system small, microkernels aim to improve reliability and security, as there is less code that can potentially contain bugs or vulnerabilities. In a microkernel architecture, additional services such as device drivers, file systems, and network protocols run in user space rather than in the kernel space. This separation allows for greater flexibility and easier updates, as these services can be modified or replaced without affecting the core kernel. Examples of microkernel systems include Mach and L4.