Customers can provision, configure and operate the servers and infrastructure resources via a graphical dashboard, or programmatically through application programming interfaces (APIs).

Typically IaaS customers can choose between virtual machines (VMs) hosted on shared physical hardware (the cloud service provider manages virtualization) or bare metal servers on dedicated (unshared) physical hardware. The difference is that the cloud service provider hosts, manages and maintains the hardware and computing resources in its own data centers. IaaS customers use the hardware via an internet connection, and pay for that use on a subscription or pay-as-you-go basis. IaaS is on-demand access to cloud-hosted computing infrastructure - servers, storage capacity and networking resources - that customers can provision, configure and use in much the same way as they use on-premises hardware. But there are additional advantages specific to each of these solutions. So the chief advantage of IaaS, PaaS, SaaS or any 'as a service' solution is economic: A customer can access and scale the IT capabilities it needs for a predictable cost, without the expense and overhead of purchasing and maintaining everything in its own data center. In cloud computing, the cloud service provider owns, manages and maintains the assets the customer consumes them via an Internet connection, and pays for them on a subscription or pay-as-you-go basis. In traditional IT, an organization consumes IT assets - hardware, system software, development tools, applications - by purchasing them, installing them, managing them and maintaining them in its own on-premises data center. 'As a service' refers to the way IT assets are consumed in these offerings - and to the essential difference between cloud computing and traditional IT. Many mid-sized businesses use more than one, and most large enterprises use all three. IaaS, PaaS and SaaS are not mutually exclusive.

SaaS, or software as a service, is on-demand access to ready-to-use, cloud-hosted application software.

PaaS, or platform as a service, is on-demand access to a complete, ready-to-use, cloud-hosted platform for developing, running, maintaining and managing applications.

IaaS, or infrastructure as a service, is on-demand access to cloud-hosted physical and virtual servers, storage and networking - the backend IT infrastructure for running applications and workloads in the cloud.

They are sometimes referred to as cloud service models or cloud computing service models.

IaaS, PaaS and SaaS are the three most popular types of cloud service offerings.

Draw use case diagram online