We are currently living in a period of rapid evolution in the way that hosted infrastructure is used to deliver software to the end-user. In the past few years we have seen this described variously as: Hosted Applications, Application Service Provision (ASP), Software-as-Service (SaaS) and Cloud Computing.

In essence these technologies have had the same principle at their cores:

The remote use of applications based on hosted servers that are either cheaper, more reliable, more feature rich or more easily managed that the traditional in-house, client-server application model.

The question we are most commonly asked is really, without all the smoke and mirrors, what are the benefits of Cloud-based applications?

The table below shows the core differences, and thus benefits, of Cloud Applications over the previous models for delivering software:

		Application Hosting	ASP	SaaS	Cloud
Central hosting
Access anytime anywhere
Central administration
Per-user-per-month charging
Scalability
Easy Scalability
Built-in High Availability
Virtualisation-based
Hybrid integration
Service development platform
Multi-service platform
Utility charging model

So, in summary, the key evolutions that Cloud Computing offers over the Software-as-a-Service model, from an application delivery perspective is this: