Virtualization

Virtualization is a technology that enables the creation of virtual versions of computing resources, such as hardware, storage devices, networks, or operating systems. By abstracting and sharing these resources, virtualization lets a single physical system run multiple independent environments, each with its own configuration and software stack.

Hardware virtualization uses a software layer called a hypervisor to present virtualized hardware to guest operating systems. Hypervisors are categorized as Type 1 (bare-metal), which run directly on host hardware, and Type 2 (hosted), which run atop a host operating system. In contrast, OS-level virtualization, or containerization, shares the host kernel while isolating user-space processes, offering lightweight virtualization with fast startup but somewhat less isolation.

How it works: The hypervisor allocates CPU, memory, storage, and I/O to each virtual machine or container. VMs run separate guest operating systems; containers share the host kernel. This isolation and portability allow VMs or containers to be moved between physical hosts with minimal changes.

Benefits include better resource utilization, easier deployment and scaling, simplified testing and disaster recovery, support for legacy applications, and security through isolation.

History: Virtualization originated with mainframes and evolved through the late 20th century, gaining broad adoption in x86 environments in the 2000s with products such as VMware. Developments include hardware-assisted virtualization, live migration, and container technologies like Docker.

Common uses include data centers and cloud computing, desktop virtualization for remote access, software testing, sandboxing, and disaster recovery planning.