user mode

In computer science, hierarchical protection domains, often called protection rings, are mechanisms to protect data and functionality from faults (by improving fault tolerance) and malicious behaviour (by providing computer security). This approach is diametrically opposite to that of capability-based security.

A modern computer operating system usually segregates virtual memory into kernel space and user space. Primarily, this separation serves to provide memory protection that protects data and functionality from faults (by improving fault tolerance) and malicious behaviour (by providing computer security).