Operating System

An operating system is system software that is responsible for the management of computer hardware, and software resources and provides requested services demanded by computer programs. 

The primary feature of OS is to provide an interface between the user and the machine. 

It is a software component of the computer system that is responsible for the management, coordination, and sharing of activities or resources of the computer. 

A  computer cannot run without the presence of an OS.

Some OS examples are as follows:- 

OS used in PC/Laptops:-  Windows, Linux, Unix, MAC, etc.
Mobile OS:-  Android, Windows, IOS, Symbian, etc.

The basic architecture of OS

Basically, OS can be divided into  4 layer architecture:-

1. Hardware
2. Operating System 
3. Software and Applications
4. User

1. Hardware Layer:-
This layer blogs to the physical part (eg; Hard Drive ) of the computer where the OS is installed. An OS is in the form of software so we need hardware (physical storage space ) for installation.

                                  

2. OS (Operating System):-  
In this layer, an OS actually exists with its all software routines and programs. Some most important parts of an OS like Kernel, Shell, etc.

3. Software and applications:- In this layer, all the installed programs reside.

4. User:-
Users cannot interact directly with OS The user can use various commands or software programs (Apps). These commands and applications are run under the control of the OS.

       
There are two interfaces through which the user can interact with OS

1. CUI (Command/ Character user interface)

2. GUI (Graphical user interface )

Process Management

Creation and deletion of a processes
Scheduling of processes

Memory Management

Allocation of memory space to needed programs.
De-allocation of memory space to needed programs.

File Management

Organizing  files
Storage of files
Retrieval of file
Naming of files
Sharing and protection of files

User Interface

Interpreting user commands
Directing system resources to process the commands

Security

OS provides the security of resources and information against destruction and unauthorized access.

Device Management

All the operations (R/w etc.) performed by the devices under the control of OS.