What is an Operating System?

An Operating System is a System software that manages all the resources of the computing device.

• Acts as an interface between the software and different parts of the computer or the computer hardware.
• Manages the overall resources and operations of the computer. 
• Controls and monitors the execution of all other programs that reside in the computer, which also includes application programs and other system software of the computer.
• Examples of Operating Systems are Windows, Linux, macOS, Android, iOS, etc.

Operating System Goals:

• Run user applications and simplify problem-solving for users.
• Ensure the computer system is user-friendly and easy to navigate.
• Optimize the use of computer hardware for efficiency

What is an Operating System Used for?

• As a platform for Application programs: It provides a platform, on top of which, other programs, called application programs can run.
• Managing Input-Output unit: It also allows the computer to manage its own resources such as memory, monitor, keyboard, printer, etc. Management of these resources is required for effective and fair utilization.  
• Multitasking: It manages memory and allows multiple programs to run in their own space and even communicate with each other through shared memory.    
• Manages memory and Files: It manages the computer’s main memory and second storage. Additionally, it allows and deallocates memory to all tasks and applications.        
• Provides Security: It helps to maintain the system and applications safe through the authorization process. Thus, the OS provides security to the system.

For more, refer to Need of Operating Systems.

Operating System Structures

The "Operating System Structures" listed here, are fundamental parts of an operating system (OS) that work together to manage hardware, software, and user interactions efficiently.

• Process Management: Manages running programs (processes), including creation, scheduling, and termination for efficient CPU use.
• Main Memory Management: Allocates and tracks RAM usage for processes, using techniques like paging and virtual memory.
• File Management: Organizes, creates, deletes, and manages access to files on storage devices.
• I/O System Management: Coordinates data transfer between devices (e.g., keyboards, printers) and the system using drivers.
• Secondary Storage Management: Manages disks (e.g., HDDs, SSDs) for data storage, retrieval, and space allocation.
• Networking: Handles communication between computers, managing protocols and data transfer.
• Protection System: Secures resources by controlling access and authenticating users.
• Command-Interpreter System: Provides a user interface (e.g., command line) to interpret and execute user commands.

Objectives of Operating Systems

Let us now see some of the objectives of the operating system, which are mentioned below.

• Convenient to use: One of the objectives is to make the computer system more convenient to use in an efficient manner.
• User Friendly: To make the computer system more interactive with a more convenient interface for the users.
• Easy Access: To provide easy access to users for using resources by acting as an intermediary between the hardware and its users.
• Management of Resources: For managing the resources of a computer in a better and faster way.
• Controls and Monitoring: By keeping track of who is using which resource, granting resource requests, and mediating conflicting requests from different programs and users.
• Fair Sharing of Resources: Providing efficient and fair sharing of resources between the users and programs.

Evolution of Operating Systems

Mainframe Systems:

• Early systems used resident monitors for job sequencing, reducing setup time.

Batch Processing:

• Grouped similar jobs to minimize setup time, improving efficiency.

Multiprocessor Systems:

• Symmetric Multiprocessing: Identical OS copies run on multiple processors, communicating as needed.
• Asymmetric Multiprocessing: A master processor controls slave processors.

Real-Time Systems:

• Hard Real-Time: Strict timing constraints for critical applications.
• Soft Real-Time: Prioritizes critical tasks with less stringent timing.

How to Choose the Operating System?

There are so many factors to be considered while choosing the best Operating System for our use. These factors are mentioned below.

• Price Factor: Price is one of the factors to choose the correct Operating System as there are some OS that is free, like Linux, but there is some more OS that is paid like Windows and macOS.
• Accessibility Factor: Some Operating Systems are easy to use like macOS and iOS, but some OS are a little bit complex to understand like Linux. So, you must choose the Operating System in which you are more accessible. 
• Compatibility factor: Some Operating Systems support very less applications whereas some Operating Systems supports more application. You must choose the OS, which supports the applications which are required by you.
• Security Factor: The security Factor is also a factor in choosing the correct OS, as macOS provide some additional security while Windows has little fewer security features.

Examples of Operating Systems 

• Windows (GUI-based, PC)
• GNU/Linux (Personal, Workstations, ISP, File, and print server, Three-tier client/Server)
• macOS (Macintosh), used for Apple's personal computers and workstations (MacBook, iMac).
• Android (Google's Operating System for smartphones/tablets/smartwatches)
• iOS (Apple's OS for iPhone, iPad, and iPod Touch)