Infrastructure as a Service was first known as Hardware as a Service in early 2006, but the term “IaaS” was quickly commercialized by firms like Savvis, ATT, and BlueLock.

Infrastructure as a Service (IaaS) shares a lot of common traits with Virtualization, except that NO physical equipment exists within the office/business premises. Think of it as a complete Virtualization of the server and network rooms.

The business critical server & network equipment is completely outsourced to a third party service provider. That service provider owns the equipment, maintains it, and keeps it safe and up to date.

Here is a list of the most popular IaaS vendors:

BlueLock vCloud
Enki Computing Utility
Enomaly Elastic Computing Platform
GoGrid Cloud Hosting
Google App Engine
Iomart Hosting
Joyent Cloud
Layered Tech
Nirvanix Storage Delivery Network
Rackspace Cloud
Terremark Enterprise Cloud
Microsoft Windows Azure
VMware vCloud API