What is an operating system?
Answer
An Operating System (OS) is a system software that manages computer hardware and software resources and provides common services for computer programs. It acts as an intermediary between the user and the computer hardware. Primary functions: (1) Process management: creating, scheduling, terminating processes and threads; (2) Memory management: allocating and deallocating memory to processes; (3) File system management: organizing, storing, retrieving data on storage devices; (4) Device management (I/O): managing device drivers and I/O operations; (5) Security and protection: controlling access to resources, user authentication; (6) Network management: networking stack, communication protocols; (7) User interface: CLI (command line) or GUI (graphical). Types of OS: Batch OS (early — no user interaction), Time-sharing/Multitasking OS (multiple users/tasks concurrently), Real-time OS (RTOS — strict timing guarantees, embedded systems), Distributed OS (multiple networked computers appear as one), Embedded OS (resource-constrained devices), Mobile OS (Android, iOS). Examples: Windows, macOS, Linux, Android, iOS, FreeBSD, Solaris. OS as resource manager: hardware (CPU, memory, I/O) is scarce and shared — OS arbitrates access, enforces policies, and ensures fair/efficient use while maintaining security boundaries between processes.