Also known as shared hosting, this form of web hosting should suffice for most everyone.
 
Virtual hosting simple refers to the fact that your site is on one server, and that this server hosts mulitple sites. You are virtually shared - your site will not be the only one on this specific server.
 
Very few sites would actually need the power of a dedicated server, so this option provides to be a reliable and cheap solution.

A dedicated server with 3 users typically cost $100/month.

Because of security reasons, we do not instantly provision a server. A server can be deployed from a template in minutes. Applications can take 24 hours (or more ) if they require vendor support

An ESX server is a physical server with VMware's ESX operating system installed on it. This operating system allows it to host more than 1 Guest Virtual Machines. Typically 2-10. See ESX Hosting.

Two main reasons:

Vigilant uses a cost effective Blade server and SAN solutions. Because these systems consolidate power, cabling, cooling,etc and provide centralized management, it does not cost us as much to host or maintain these systems as traditional, discreet server systems

Unlike many ESX/Vmware hosting providers, Vigilant has been hosting Virtual solutions since 2004. So we have learned many ways to reduce cost of virtual solutions.

Vigilant uses IBM, HP or Dell blade server systems. We primarily use IBM Bladecenter servers (see "why bladecenter" article).

For storage, we use cloud storage systems (smaller storage arrays with multiple nodes)  vs single head (1/2 controllers and multiple shelves with 3-40 terbytes)

Vigilant actually uses several Datacenters. Our Datacenter providers are:

• i/o Datacenters
• Integra Telecom
• 365 main
•  Sterling (digital Realty)

We primarily use datacenters in Phoenix because because of the great power/bandwidth resources and low proability of disaster.

In a nutshell, cloud computing is an approach to computing that leverages the efficient pooling of an on-demand, self-managed virtual infrastructure, consumed as a service.

Private clouds or internal clouds operate on private networks so resources are only accessible by a single company. Over 45% of enterprise deployments are private clouds because of their advantages in data security, corporate governance and reliability.

Hybrid clouds combine the benefits of private and public clouds, and are growing in popularity, with nearly 20% of enterprise deployments using this model today. Hybrid clouds offer flexibility and choice of deployment methods between public and private clouds, and maximise value without compromising on performance, control and security. When combined with our Virtual Disk optimization and client-side de-duplication technologies the cure finally does not kill the patient

Public clouds offer IT resources as a service through external service providers and are shared across multiple organizations. 35% of enterprise deployments currently use this model.