Virtualization Basics

WHAT

Virtualization: A system that abstracts hardware/software and provides virtual instance of computer hardware platforms, applications, storage devices and network resources

WHY

• Server consolidation 
• Software development (e.g. cross-platform programming, continuous integration)
• Legacy systems support ( old games)
• Isolation and Security
• Cloud infrastructure
• Network function virtualization (e.g. switch, router)

HOW

Machine-level virtualization

System virtual machine: provides a substitute of a real machine, hypervisor: xen, kvm, virtualbox etc
Process/Application virtual machine: provides platform-independent environment,  e.g. JVM .NET framwork

OS-level virtualization

provides guest  system a shared operating system, e.g. FreeBSD jails, Docker, LXC

REFERENCES

1. https://systems.cs.columbia.edu/projects/kvm-arm/
2. https://en.wikipedia.org/wiki/Virtual_machine