What role does a hypervisor provide for each virtual machine in server virtualization?

A hypervisor is a layer of software that sits between the physical hardware and the virtual machines (VMs). Its primary role is to create and manage VMs, allocating and controlling access to the underlying physical resources like CPU, memory, storage, and network interfaces for each VM. This allows multiple operating systems and applications to run concurrently on a single physical server, isolated from each other. Infrastructure-as-a-Service (IaaS) and Software-as-a-Service (SaaS) are cloud computing service models, not the direct role of a hypervisor. While hypervisors are fundamental to IaaS, they are a component, not the service model itself. A hypervisor does not act as a hardware controller; it manages the virtual environment that interacts with the hardware.