什么是虚拟化（virtualization）
首先是wiki上面对于虚拟化的定义
In computing, virtualization refers to the act of creating a virtual (rather than actual) version of something, including virtual computer hardware platforms, storage devices, and computer network resources. Virtualization began in the 1960s, as a method of logically dividing the system resources provided by mainframe computers between different applications. Since then, the meaning of the term has broadened. from https://en.wikipedia.org/wiki/Virtualization
如今的虚拟化，wiki百科上面被分为几个种类，主要有以下三种：
硬件虚拟化（Hardware Virtualization）
Desktop virtualization
Nested virtualization
硬件虚拟化
硬件虚拟化。其核心定义是创建一个能够像真的操作系统一样活动的虚拟机（virtual machine