What is a monolithic kernel and a microkernel?

The kernel is the heart of an operating system.

The kernel internally contains many components, such as a memory manager, scheduler, numerous device drivers, a file system, and so on. When an operating system is being written, there are numerous design philosophies which the designers can adopt. At one extreme is the monolithic kernel, in which all of the components mentioned above, and many others, are all lumped into a single operating system file. At the other extreme is the microkernel, where only the bare minimum is put into the kernel file, and every thing else is put into separate programs, which the microkernel loads and runs at boot time.

In practice, the design of most operating systems lies somewhere in between those two extremes, although they generally tend to be closer to a monolithic kernel than a microkernel. But, like everything else in life, the microkernel has its true believers.

Other Answer:

In monolithic operating system all services are provided in the operating system kernel itself. In my own understanding, monolithic operating system is one big program. Being 'one big program' all the services are associated with one another. This is prone to system crashes, because, if one particular function fails, the entire system will be brought to halt. In regards to resource management, it is difficult for the programmer to debug or implement the system. The only advantages of being monolithic are it deals with resource management rapidly. An example of a monolithic operating system will be the UNIX and MS-DOS. In microkernel operating system, processes are divided and stored in a different server. This key concept of the microkernel operating system is to keep the OS kernel small with basic and minimum process. Other services are stored in a different server. They communicate, via a communication channel