There are two types of hypervisors: Type 1 and Type 2. Type 2 hypervisors support guest virtual machines by coordinating calls for CPU, memory, disk, network and other resources through the physical host's operating system. This makes it easy for an end user to run a virtual machine on a personal computing device. Examples of this type of hypervisor include VMware Fusion, Oracle Virtual Box, Oracle VM for x86, Solaris Zones, Parallels and VMware Workstation.
In contrast, a Type 1 hypervisor (also called a bare metal hypervisor) is installed directly on physical host server hardware just like an operating system. Type 1 hypervisors run on dedicated hardware. They require a management console and are used in data centers. Examples of this type of hypervisor include Oracle OVM for SPARC, ESXi, Hyper-V and KVM.
Regardless of the implementation, virtual machines (VMs) and their guest operating systems are typically unaware of which type of hypervisor is implemented, as they interact only with the hypervisor itself.
See also: client hypervisor