Hypervisors are the core technology behind virtualization. They enable the creation of virtual machines, which are self-contained computing environments that run on a single physical machine. Hypervisors are a fundamental element of cloud computing, data centers, and virtualized IT environments, allowing for greater flexibility, resource utilization, and scalability. In essence, they transform a single computer into a platform for multiple virtual machines, each running its own operating system and applications. This makes it possible to efficiently use the power of modern hardware while maintaining isolation and security between virtualized environments.

Virtual machines ( VMs ) can be moved to different computers with ease because they operate independently of the physical hardware. They use virtualized hardware, which is the same across different computers. VMs are like software packages with their own settings and data, making them portable. This means you can transfer a VM from one computer to another and run it as long as the new computer supports the same virtualization technology.

There are two types of Hypervisors:

Type 1 hypervisors have direct access to the host system's hardware, including CPU, memory, and storage. This direct connection translates to superior performance, making them a preferred choice for demanding enterprise environments. They efficiently allocate physical resources available to multiple virtual machines ( VMs ). This ensures that CPU cores, memory, and storage are utilized optimally.

VMs running on Type 1 hypervisors are isolated from one another. This isolation not only enhances security but also means that issues within one VM do not apply to others. Notable Type 1 hypervisors include VMware vSphere/ESXi, Microsoft Hyper-V ( when installed directly on hardware ), and Proxmox. They are used in various environments, from data centers to cloud settings, where many essential tasks are performed.

In essence, Type 1 hypervisors stand at the forefront of server virtualization, offering a robust and efficient way to create and oversee virtual machines directly on the physical hardware. They are commonly used in data centers and cloud environments to host virtual machines that run critical workloads.

Type 2 hypervisors are a form of virtualization technology that allows you to run multiple operating systems on a single computer. Unlike Type 1 hypervisors that run directly on the computer's hardware, Type 2 hypervisors work on top of your regular operating system, like GNU/Linux, MacOS or Windows. Once installed, they create a virtual environment where you can run other operating systems. These virtual machines ( VMs ) are like separate, isolated computers running within your main computer.

Type 2 hypervisors are often used for tasks like development, testing, or running specific software that might not be compatible with your main operating system. For example, if you're using a Mac but need to run a Windows program, a Type 2 hypervisor lets you do that in a virtual Windows environment.

Popular examples of Type 2 hypervisors include Oracle VirtualBox, VMware Workstation, and Parallels Desktop (for macOS). They are generally user-friendly and don't require special hardware or complex setup. You can allocate CPU, memory, and storage to each VM, and these VMs are isolated from your main operating system, so if something goes wrong in one VM, it usually won't affect your computer.

While Type 2 hypervisors are convenient for certain tasks, they may introduce some performance loss compared to Type 1 hypervisors.