Core isolation is a Windows Security section that groups protections meant to keep the most sensitive parts of the operating system separated from the rest of the machine. It is closely associated with virtualization-based security (VBS) and features such as Memory integrity, which use the hypervisor to protect critical kernel code and memory in a more isolated environment.
This matters because many serious Windows attacks target the kernel, drivers, or other privileged components. If an attacker can load a malicious driver or corrupt kernel memory, they may gain deep control over the system. Core isolation raises that bar by making code integrity checks and memory protections harder to bypass. For defenders, it is a practical hardening control: enable it where hardware and drivers support it, test incompatible drivers before rollout, and verify status in the Device security area of Windows Security.