Know your computer OS and Application software in simple

What is an OS (Operating System) software in computer system?

Definition:    OS software is a bunch of programs which manage different hardware attached to system.

It facilitates communication between hardware which in return ensures effective utilization.

It facilitates power to Application programs and Users for using hardware .

A system without OS is simply dump of hardware.

Example of available OS:   Android, BSD, iOS, Linux, Mac OS X, Microsoft Windows, Windows Phone, and Z/OS. All these, except Windows and Z/OS, share roots in Unix.

What is an Application Software in computer system?

Definition:    Application software is a computer program which is made for specific application(job).

It make computer to work in a specific order to give desired result output require by user.

Example of available Application software:   Word processing software, Photo processing software, PDF reader, Notepad  etc..

In this diagram, user is at the top and hardware is at bottom. It shows OS work on Hardware, Application software work on OS and user work on Application software.

Layman understanding of OS and Application software
To understand in simple language a computer and functioning of its related components, let us see a  comparison between computer system(made by human) and Human(made by nature). Although there is no comparison between a man(an intelligent machine) and a machine, but for the shake of simplicity.

Computer system	Example in Human
Computer without OS	Man without life just like "Dead body", who cannot able to use its hardware (body parts) like - eye, nose, ear, hand, legs etc..
Computer with some kind of OS	A "Common man" (un-educated one) who can perform its own day to day primary work, like eating, walking, running etc.. Although he is un-educated but still got the knowledge(or capability) of utilizing all its hardware(body part) like -  eye, nose, ear, hand, legs etc. This knowledge is not a single one instead a bunch which cover almost all its body part(one for each part). This knowledge acting like OS for that person.
Computer with an advance OS version	An "Educated man" who keep all general know-how of world around him, like reading newspaper, writing, web surfing, going to its job etc.. He able to perform all the jobs of a "common man" with added smartness and efficiency.
Computer with OS and Application software	A "Doctor" who can perform all the jobs of an "Educated man" with and added expertise in medical field. He can perform medical checkup and take the remedial actions in case of disease in human body. This technical knowledge work like an Application software which is meant for a particular application.
OS is loaded through CD/DVD	OS loading through learning, experience and observation.

What makes a human different than a computer?
If you say technically, human is a great machine ever made by nature on earth.
Computer works as per the instruction given in its software, but human can make their own set of  instructions (on the basis of knowledge, experience and observation) for their work.