📖 14. Protection

📖 From Operating System • 275 questions available

About 14. Protection

Protection is a mechanism within the OS that controls which processes, users, or programs can access which resources. Its primary goal is to prevent accidental or deliberate interference with system operation. Think of it as the security guard of the system that enforces rules to keep everything in order. It ensures that one user's files are not accessed by another without permission, and that a regular application can't accidentally modify the core OS code, which could crash the entire system.

This is typically achieved by distinguishing between different "modes" of operation, such as "user mode" and "kernel mode." User programs run in user mode, where they have limited access to hardware and system data. When a program needs to do something privileged, like accessing a file or hardware, it makes a request to the OS via a "system call," which switches the system to kernel mode. The OS then checks if the user has the necessary permissions before performing the action. This separation creates a wall of safety that protects the system's integrity.

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🔄 Last updated: 2026-07-27