#1- Operating system

OPERATING SYSTEM-

  An operating system (OS) is software that acts as an interface between computer hardware and user application. it manages the resources and provides services for the efficient and secure execution of program.

*"they all need to access your computer's central processing unit (CPU), memory, and storage. The operating system coordinates all of this to make sure each program gets what it needs"

There are several types of operating systems, including:

1. windows: development by Microsoft, windows is a widely used operating system for personal computer.

2.macOS: development by Apple, macOS is the operating system used on apple Mac computers. 

3. Android: development by Google, Android is an open-sources(including anything no security) operating system primarily designed for mobile devices such as smartphone and tablets. 

4. iOS: development by Apple, iOS is the operating system used on iPhone, iPad, iPods. it provides a seamless and secure user experience, focusing on  performance and integration with other Apple devices.

5.  Unix: Unix is a powerful multi-user operating system that served as the foundation for many other operating systems, including Linux and macOS. 

6. Linux: Linux is an open-sources operating system that is highly customizable and widely used in server environments and embedded system.

7.RTOS: (Real time operating system): RTOS is designed for systems that required deterministic and real-time response. it is commonly used in embedded systems, controls systems, and IoT devices.