The main advantage of using a virtual machine (VM) is its ability to emulate a separate computer environment within a physical machine. This allows multiple operating systems to run concurrently on the same hardware, offering flexibility for software development, testing, and deployment. VMs provide resource isolation, enhanced security, and simplified management of different systems. They also reduce hardware costs as multiple VMs can run on a single physical server, optimizing resource utilization. Additionally, VMs can be easily backed up, cloned, and migrated across different platforms or infrastructures.