Hypervisor is virtual machine monitor (VMM) that enables numerous virtual operating systems to simultaneously run on a computer system. These virtual machines are also referred to as guest machines and they all share the hardware of the physical machine like memory, processor, storage and other related resources. This improves and enhances the utilization of the underlying resources.

The hypervisor isolates the operating systems from the primary host machine. The job of a hypervisor is to cater to the needs of a guest operating system and to manage it efficiently. Each virtual machine is independent and do not interfere with each another although they run on the same host machine. Even at times when one of the virtual machines crashes or faces any issues, the other machines continue to perform normally.

There are two major classifications of hypervisors to be aware of.  Type-1 and Type-2 both do the same basic task, but the way they do it is quite different from each other.

Type-1 hypervisors run directly on the hardware. In other words they require no software or operating systems to be installed ahead of time and install right onto the hardware you want to run them on. Hyper-V Server and ESXi are two examples of this type of hypervisor that is used in many places today.  The benefit of a Type-1 hypervisor is direct access to the physical hardware.

While type-1 hypervisors are very powerful, they are complex platforms that require a great deal of specialized knowledge to run. They also tend to have strict hardware requirements to run properly. Although they are perfect for IT operations, they are not the best fit for casual configurations or desktop work. The second type of hypervisor fills this gap.

Type-2 hypervisors are designed to install onto an existing operating system. They tend to have a much lower learning curve, and require far less in terms of hardware horsepower to function, but this comes at a price. Type-2 hypervisors typically cannot run more complex virtual workloads or high-utilization workloads within virtual machines. They’re designed for basic development, testing and emulation tasks such as running Windows software on a Mac.