**Virtualization** is a technology that creates abstract representations of physical computing resources—including [[Server (computing)|servers]], [[Computer data storage|storage]], [[Computer network|networks]], and [[Operating system|operating systems]]—allowing multiple isolated virtual instances to run on a single physical system or enabling physical resources to be pooled and allocated flexibly across workloads. By inserting a software abstraction layer between hardware and the software that uses it, virtualization decouples resource consumption from physical resource ownership, improving utilization, flexibility, and manageability across [[IT infrastructure|IT infrastructure]]. The technology is foundational to modern [[Cloud computing|cloud computing]], [[Data center|data center]] operations, and [[Software development|software development]] environments. The most prevalent form of virtualization is **server virtualization**, in which a [[Hypervisor|hypervisor]]—also called a virtual machine monitor (VMM)—runs on physical hardware and manages multiple [[Virtual machine|virtual machines]] (VMs), each presenting a complete virtualized hardware environment to its [[Guest operating system|guest operating system]]. **Type 1 hypervisors**, or bare-metal hypervisors, run directly on the host hardware without an intervening operating system, and include [[VMware vSphere|VMware ESXi]], [[Microsoft Hyper-V|Microsoft Hyper-V]], and [[Kernel-based Virtual Machine|KVM]]. **Type 2 hypervisors** run as applications atop a conventional operating system and are used primarily in development and desktop contexts, with examples including [[VMware Workstation|VMware Workstation]] and [[Oracle VM VirtualBox|VirtualBox]]. Each virtual machine is isolated from others on the same host, with the hypervisor managing the allocation of physical [[CPU|processor]], [[Random-access memory|memory]], and [[Input/output|I/O]] resources across competing VMs. Virtualization extends beyond server consolidation to encompass several related disciplines. **[[Storage virtualization|Storage virtualization]]** abstracts physical storage devices into logical pools managed independently of underlying hardware, as implemented by [[Storage area network|storage area networks]] (SANs) and software-defined storage platforms. **[[Network virtualization|Network virtualization]]** abstracts network resources into software-defined constructs, enabling technologies such as [[Virtual LAN|VLANs]], [[Virtual private network|VPNs]], and [[Software-defined networking|software-defined networking]] (SDN). **[[Desktop virtualization|Desktop virtualization]]**, including [[Virtual desktop infrastructure|virtual desktop infrastructure]] (VDI), delivers desktop environments hosted on centralized servers to end-user devices. **[[Container (virtualization)|Containerization]]**, exemplified by [[Docker (software)|Docker]] and managed at scale by [[Kubernetes]], provides a lighter-weight form of operating system-level virtualization that isolates application processes without requiring separate guest operating system instances, offering greater density and faster startup times than traditional VMs at the cost of reduced isolation boundaries.