This report provides a comprehensive overview of operating systems, serving as an interface between computer hardware and users. It explores essential functions like memory, process, and file management, along with input/output handling and peripheral device control. The report delves into the services offered by Windows and Linux operating systems, including input/output operations, pipes and filters, access control, process management (threads, parallel processing, concurrency), scheduling, and memory management (stack, heap, shared memory, virtual memory, addressing, paging, swapping, buffers, and ring buffers). Furthermore, the report evaluates and compares Windows and Linux, highlighting security risks such as malware, viruses, and vulnerabilities like buffer overflows, along with security management strategies and access control mechanisms. The report concludes by emphasizing the critical role of operating systems in facilitating user-hardware interaction and enabling diverse computing activities.