Cloud computing is the use of computing resources (hardware and software) that are delivered as a service over a network (typically the Internet). - Wikipedia
According to Wikipedia currently there are few popular service models exist.
1. Infrastructure as a service (IaaS)
2. Platform as a service (PaaS)
3. Software as a service (SaaS)
So, I have an Eucalyptus cloud, which is great, serves as AWS-like IaaS platform.