Cloud Service Provider (CSP): A CSP is the entity operating a given cloud service. In a SaaS scenario, this is simply the application provider. In an IaaS or PaaS scenario, the CSP may be the underlying IaaS/PaaS infrastructure provider or the owner of the application running on that platform. In all cases, the CSP is the thing that holds the identity information being operated upon. Put another way, the CSP really is the service that the end user interacts with.