1.3.1 What is kernel in operating system with explanation of user mode and kernel mode in details

Описание: Kernel is an interface between System Hardware and Application Software.
Kernel is also known as heart or core of operating system, kernel is a power full part of operating system, capacity and working of operating system mostly depended on it's kernel. All operating systems are using their own kernel building technology.

Earlier System or Mainframe computer was starting of computer society. There were many limitations on that machines but still at that time it was wonder for people.

Later on many operating systems arrived like,
Batch System, Spooling, Multi programming, Multi tasking, and Multiprocessing.

Now a days we are using further developed operating systems like distributed systems, network operating systems and real time operating systems.

Mainly operating system is an interface between user and computer hardware. User is applicable to interact with computer only by the operating system.

Primary goal of operating system is to provide convenience and secondary goal of operating system is to provide efficiency.

Basically operating system is working as a resource manager as well as for the resource allocation also.

Functions of Operating Systems are like, User interface, Resource management, Process Management, Memory Management, Input Output Management, File Management, Security Management and many more.

Operating system is structured in monolithic and micro kernel structure as well as in layered architecture also. Now a days virtual machines are also used in operating systems.