We own and manage all the hardware and software for an application on-premises. With cloud computing, cloud service vendors provide three models for us: IaaS, PaaS, and SaaS.

IaaS: provides access to cloud vendors' infrastructure, like servers, storage, and networking. We pay for the infrastructure and install and manage supporting software on it for our application

PaaS: goes further. It provides a platform with various middleware, frameworks, and tools to build our application. Our sole focus is application development and data

SaaS: enables the application to run in the cloud