Amazon Web Services essentially put the words cloud and Infrastructure as a Service (IaaS, in its abbreviated form) into the IT dictionary. I'm not implying that Amazon Web Services invented cloud computing, not at all! The creation of cloud computing is a multi-faceted story that took time and organic growth to become what it is today. I am simply implying that Amazon Web Services was the one that really made your typical enterprise start thinking of IT as services instead of investments.
Cloud computing can be broken down into three categories that define what kind of service is being consumed from the cloud, that is, Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS). The following diagram illustrates the services that are offered by each service layer:
