虚拟化virtualization
Virtualization
虚拟化是计算机系统在实际硬件上的一层抽象，来运行虚拟实例。最常见的，是同时在一个计算机系统上运行多个操作系统。
CPU的虚拟化技术可以单CPU模拟多CPU并行,允许一个平台同时运行多个操作系统,并且应用程序都可以在相互独立的空间内运行而互不影响,从而显著提高计算机的工作效率。
为什么利用虚拟化进行计算？
desktop users, 可以运行多个操作系统的应用而不用切换计算机或者reboot登录系统。
administrators of servers, 虚拟化运行不同的操作系统，更重要的，提供了一个方式将大的操作系统分段成更小的部分，允许服务器更有效的利用（不同用户或者英语的不同需求）。
也支持isolation, 保证运行在一个虚拟机内部的进程安全，以及不受相同host上的另一个虚拟机进程打扰。
What is a hypervisor?
What is virtual machine?
是一个电脑系统的仿真，运行在另一个系统之上。Virtual machines可以获得任意数量的资源，computing power, through hardware-assisted but limited access to the host machine's CPU and memory;one or more physical or virtual disk devices for storage; a virtual or real network inferface; as well as any devices such as video cards, USB devices, or other hardware that are shared with the virtual machine. If the virtual machine is stored on a virtual disk, this is often referred to as a disk image. A disk image may contain the files for a virtual machine to boot, or, it can contain any other specific storage needs.
The difference between a container and a virtual machine?
Linux containers,和虚拟机概念上相似，功能上有所不同。都允许在隔离的环境运行应用程序，允许堆叠多个在同一个机器中就像他们都是独立的计算机一样。
A container is actually just an isolated process that shared the same Linux kernel as the host operating system, as well as the libraries and other files needed for the execution of the program running inside of the container, often with a network interface such that the container can be exposed to the world in the same way as a virtual machine. Typically, containers are designed to run a single program, as opposed to emulating a full multi-purpose server.
https://opensource.com/resources/virtualization
https://www.redhat.com/en/topics/virtualization?intcmp=7016000000127cYAAQ