IaaS (Infrastructure as a Service) -The vendor provides organizations with servers, storage, and networking devices. The infrastructure is scalable depending on the package the organization purchases. IaaS can be in the form of physical data centers where the vendor manages the data center and provides access to the organization. IaaS can be in the form of computers where the needed computers are virtualized. The vendor manages the hypervisor and the organization provisions the instances. IaaS can be in the form of networking where the vendor makes available traditional router and switches programmatically through APIs. The vendor manages the hardware and the organization programs the hardware. IaaS can be in the form of storage such as data cluster storage. The IaaS manages the hardware on which the data resides and the organization manages their own data.
PaaS (Platform as a Service) –The vendor provides organizations with an environment to develop, manage, and deliver applications. The organization can develop their applications without having to focus on servers, operating systems, other software involved, or backups. The vendor provides management for the servers, the operating systems, the server software, and the backups.
SaaS (Software as a Service) –The vendor provides the organization with access to software somewhat virtually. The organization does not install the software on their machines because it is accessed from the vendors cloud through the web or an API. The vendor manages the software upgrades and the organizations data storage of saved files through the application. The organization can scale its storage of data resource usage depending on the package they purchase.