A virtual machine (VM) is a digital version of a physical computer. Virtual machine software can run programs and operating systems, store data, connect to networks, and perform other computing functions, and requires maintenance such as system updates and monitoring. Multiple virtual machines can be hosted on a single physical machine, often a server, and then managed by virtual machine software. This provides flexibility for computing resources (compute, storage, network) to be distributed among virtual machines as needed, increasing overall efficiency. This architecture provides the building blocks for the advanced virtualized resources we use today, including cloud computing.