Which technology allows a computer to resemble multiple computers running concurrently?

Virtualization is the technology that enables a single physical computer to function as multiple virtual machines (VMs). Each virtual machine operates as an independent system, running its own operating system and applications, which allows for resource optimization and increased flexibility in computing environments. By abstracting the underlying hardware, virtualization allows multiple operating systems and applications to run concurrently on the same physical hardware, facilitating better resource allocation and management.

This capability is crucial in various scenarios such as server consolidation, software development, and testing environments, where different environments are often required simultaneously without the need for additional physical hardware. Virtualization provides a cost-effective way to maximize the use of physical resources while maintaining isolation between different virtual machines.

In contrast, threading refers to the division of a program into smaller, parallel executable components, while clustering involves connecting multiple computers to work together as a single system. Multi-core processing refers to a single processor with multiple cores that can execute multiple instructions simultaneously, but it does not provide the same level of operational independence as virtualization.