AWS Compute uses Multi-Tenancy

EC2 instances are virtual machines (VMs). VMs share an underlying physical machine with other instances (this is called multi-tenancy).  This is enabled by software called a hypervisor. VMs are isolated but share resources.

When you provision an EC2 instance, you can choose the operating system as Windows or Linux. You can provision thousands of EC2 instances on demand. They are resizable so you can start small and then give your instance(s) more memory and CPU.  This is the "elastic" nature of EC2 and is known as vertically scaling an instance. You can also control networking in EC2. Essentially you can choose what requests get to your server.

Virtualization is not a new concept; but AWS makes it more convenient to acquire servers via its Compute-as-a-Service model.

Virtualization on Windows - And Why you Need it Now

VMware Player allows you to run virtual machines on Windows (or Linux)...but on this blog we are only interested in Windows! The current version is 2.5. It's used to operate VMs created by VMware Workstation, VMware Fusion, VMware Server or VMware ESX and Microsoft Virtual Server and Microsoft Virtual PC virtual machines. Woo hoo! If you want to run Sage (open source math application) on Windows YOU NEED VMWARE PLAYER!!!

A lot of investment is going on in hypervisor technology.

Hypervisors may include software or hardware used to create virtual machines. They are also known as VMMs or virtual machine monitors, and are referred to as hosts, with the VMs they create being known as guests. The term hypervisor is actually quite old in computer terms, it dates from 1974 in an article by Gerald Popek (PhD mathematician from Harvard, later to taken on various CTO roles) and Robert Goldberg. They came up with the hypervisor classification of Type 1 (bare metal, or the "old IBM way") and Type 2 ("software way") which is adopted by many companies such as VMWare. A Type 2 hypervisor is also known as a "hosted hypervisor".

A lot of dynamics around the industry are changing in the area of virtualization.