Virtualization.
What is a Virtual Machine?
A virtual machine is a tightly isolated software container that can run its own 
operating systems and applications as if it were a physical computer. A virtual machine behaves exactly like a physical computer and contains it own virtual (ie, software-based) CPU, RAM hard disk and network interface card (NIC).
An operating system can’t tell the difference between a virtual machine and a physical machine, nor can applications or other computers on a network. Even the virtual machine thinks it is a “real” computer. Nevertheless, a virtual machine is composed entirely of software and contains no hardware components whatsoever. As a result, virtual machines offer a number of distinct advantages over physical hardware.
What is Virtualization?
Virtualization essentially lets one computer do the job of multiple computers, by sharing the resources of a single computer across multiple environments. Virtual servers and virtual desktops lets you host multiple operating systems and multiple applications locally and in remote locations, freeing you from physical and geographical limitations. In addition to energy savings and lower capital expenses due to more efficient use of your hardware resources, you get high availability of resources, better desktop management, increased security, and improved disaster recovery processes when you build a virtual infrastructure.
What is a Virtual Infrastructure?
In essence, a virtual infrastructure is a dynamic mapping of physical resources to business needs. While a virtual machine represents the physical resources of a single computer, a virtual infrastructure represents the physical resources of the entire IT environment, aggregating x86 computers and their attached network and storage into a unified pool of IT resources.
Structurally, a virtual infrastructure consists of the following components:
- Single-node hypervisors to enable full virtualization of each x86 computer.
- A set of virtualization-based distributed system infrastructure services such as resource management to optimize available resources among virtual machines.
- Automation solutions that provide special capabilities to optimize a particular IT process such as provisioning or disaster recovery.
By decoupling the entire software environment from its underlying hardware infrastructure, virtualization enables the aggregation of multiple servers, storage infrastructure and networks into shared pools of resources that can be delivered dynamically, securely and reliably to applications as needed. This pioneering approach enables organizations to build a computing infrastructure with high levels of utilization, availability, automation and flexibility using building blocks of inexpensive industry-standard servers.
