VMWare ESXi is an installable/embeddable virtualization platform based around the ESXi Hypervisor.

VMWare ESXi is a type 1 hypervisor based virtualization platform that installs on bare hardware (no host OS required) that allows running multiple guest virtual machines simultaneously.

ESXi is available freely with basic single-server functionality, but more advanced functionality requires licensing commercial versions of VMWare vSphere (formerly known as VMWare Infrastructure prior to version 4.0). ESXi lacks the linux-based service console included with VMWare ESX, further reducing install footprint and attack surface.