Let us briefly touch upon what a virtual machine truly comprises. A virtual machine exists in an abstract form as a set of files. The files themselves are directly, or indirectly, representative of the virtual hardware components and configuration settings that the guest operating system will need at runtime. We shall discuss the files that make up the virtual machine and their respective uses later in the chapter. In simpler words, a virtual machine can be created, copied, or destroyed with basic file manipulation operations. This very attribute of the virtual machine enables a plethora of features, such as agility, availability, security, and portability.

A virtual machine is initially populated with the following default virtual hardware:

Memory, CPUs, a SCSI controller, hard disks, and network adapters
Video card, VMCI device, CD/DVD drive, and floppy drive

Components can be added or modified at the end of the virtual machine creation wizard, or by using the Edit Settings wizard at any time during the life cycle of the VM. The wizard presents the following components:

Hard disk (new/existing/RDM)
Network adapter
CD/DVD drive
Floppy drive
Serial port, parallel port, host USB device, and USB controller
SCSI device, PCI device, and shared PCI device
SCSI controller, NVMe controller, and SATA controller