What is the name of the software layer that allows multiple virtual machines to share a single operating system or hardware resources?

The software layer that enables multiple virtual machines to share a single operating system or hardware resources is known as a hypervisor. A hypervisor creates and runs virtual machines by abstracting the underlying hardware. It allows each virtual machine to operate independently, providing isolated environments for different operating systems to run on the same physical hardware. This capability is crucial for efficient resource utilization, enabling better management, scalability, and flexibility in computing environments.

In contrast, a loader is a program that loads executable files into memory, but it does not manage virtual machines. A virtual manager isn't a standard term widely recognized in the field and does not refer specifically to the software layer that manages virtual machines. Lastly, while containers provide a lightweight alternative for virtualization by packaging applications and their dependencies, they do not offer the same level of hardware abstraction and isolation that a hypervisor provides, as containers share the host operating system kernel.