PVM, or Parallel Virtual Machine, is a software tool that enables a collection of computers to work together as a single, unified system. It allows users to run parallel applications by coordinating the resources of multiple machines, which can improve performance and efficiency for complex computations. PVM is commonly used in high-performance computing environments, such as research institutions and universities, where large-scale simulations and data processing tasks are required. By facilitating communication between different machines, PVM helps researchers and engineers tackle problems that would be too time-consuming or resource-intensive for a single computer.