Well here goes, how to explain Virtualisation in less than 500 words!

Virtualisation enables multiple servers or desktops to share the hardware resources of, and run on one physical computer! Consider that what we usually refer to as ‘the server’ is really just a more powerful computer, usually with more storage space. The actual ‘Server’ element is not the hardware, but what it serve’s, which is done by software (e.g. Windows Server 2012 is Server Software).

Virtualisation simply makes to most of this concept, if the server is just a software resource, why does it need its own hardware, why shouldn’t it share the same hardware as other software? This is no different a concept to having multiple programs installed on your home PC.

Futuristic Touchscreen Interface
So where you have your Operating System on your home computer (maybe Windows 7), which is software, and it enables other software, such as Microsoft Office, or Sage Accounts to run on the same computer. In Virtualisation you simply have a Hypervisor which is software, that runs on a computer and enables other software such as multiple copies of Windows Server 2008 or 2012 to run on the same computer.
We refer to Virtual computers as Virtual Machines or VM’s, and the Physical Computer that the VM’s reside on as Virtual Host Servers. The Virtual Host Servers can each support many VM’s, they just need to have the correct hardware specified accordingly, for example if you are going to virtualise 2 servers, and each needs 100Gb Disk Space, and 8 Gb RAM, you need to ensure you have 200Gb Free Space and 16Gb Free RAM on your Host Server.

Virtualisation Benefits

There are obvious benefits to virtualisation, such as lower power consumption, takes up less space, generates less Co2 and Heat, costs less money, because you require less physical hardware.
There are also other less obvious, but more advantageous benefits of virtualisation, such as greater flexibility, scalability, reliability and resilience. Undoubtedly more difficult to quantify, however very significant in terms of maximising return on investment.
The following 4 minute clip helps to demonstrate virtualisation

Types of Virtualisation

Server Virtualisation, Click Here to read more about Server Virtualisation and the options around high availability and clustering.
Desktop Virtualisation or VDI, Click Here to read more about Desktop Virtualisation or VDI technology, and how it can dramatically reduce your IT bills and extend the life of your desktop/laptop hardware.