The types of virtual machine resources can be categorized as:
Virtual machine templates: Reusable virtual machine templates used to create multiple virtual machines.
Assemblies: Template containing a configuration of multiple virtual machines with their virtual disks and the inter connectivity between them.
ISO files: DVD/CD image files used to create virtual machines from scratch using the installation media.
Virtual disks: Virtual disks used by virtual machines to perform boot operations, to run the operating system, and to extend the storage capability of virtual machines.
Virtual machine files: Configuration files of your virtual machines.
Virtual machines can be created from different types of resources: either from a template or assembly containing preconfigured virtual machines, or from scratch using an ISO file (image) of an installation DVD. Booting a virtual machine via PXE, or network boot for a paravirtualized guest, is also possible.