Which type of hypervisor needs an underlying operating system?

A Type 2 hypervisor operates on top of an existing operating system, utilizing the host OS's resources and capabilities to manage virtual machines. This means it relies on the underlying operating system for tasks such as memory management, device drivers, and input/output operations. As a result, Type 2 hypervisors are often easier to install and use, especially for personal or small-scale environments, since users can run them like any regular application within their OS.

In contrast, a Type 1 hypervisor runs directly on top of the hardware without needing a host operating system. This direct interaction with the physical hardware allows for better performance and resource management, making Type 1 hypervisors more suitable for enterprise-level applications and large-scale environments. The other types mentioned in the question, such as Type 3 and Type 4 hypervisors, are less commonly referenced in standard virtualization terminology, as they do not align with the conventional classification of hypervisors.