In computing, x86 virtualization is the facility that allows multiple operating systems to simultaneously share x86 processor resources in a safe and efficient manner, a facility generically known as hardware virtualization. In the late 1990s x86 virtualization was achieved by complex software techniques which overcame the processor's lack of virtualization support and attained reasonable performance. In the mid 2000s, both Intel and AMD added hardware support to their processors making virtualization software simpler, and later hardware changes provided substantial speed improvements.

The following discussion focuses only on virtualization of protected mode of the x86 architecture.

In protected mode the Kernel runs at a higher privilege such as ring 0, and applications at a lower privilege such as ring 3. Similarly, a host OS must control the processor while the guest OS' are prevented from direct access to the hardware. One approach used in x86 software-based virtualization is called ring deprivileging, which involves running the guest OS at a ring higher than 0.