What are three 3 key aspects of cloud computing?

What are three 3 key aspects of cloud computing?

Cloud computing can be broken up into three main services: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). These three services make up what Rackspace calls the Cloud Computing Stack, with SaaS on top, PaaS in the middle, and IaaS on the bottom.