IMHO, virtualization is about what resource you want to hold constant and what you want to scale. The most popular version of virtualization is where one fixes the hardware configuration and scales on hosting environment. This type of virtualization done by VMWare/Xen etc. is what most people think of when one says virtualization. We can generalize this to define virtualization types based on which one or two resources one holds constants and which ones one scales.
I think virtualization as a field is function of hardware, hosting environment, collective and application and of course the user (identity).
| Virtualization Types |
Hold Constant | Scaling Dimension | Type |
| Hardware | Hosting Environment | VMWare Type |
| Hosting Environment | Hardware | Grid Type |
| Hardware & Hosting Environment | Identity | Single Sign On |
| Hardware, Hosting Environment, Identity | Applications | Web Application Delivery Type |
