IaaS, PaaS, and SaaS are three distinct cloud service models. What these categories have in common is that they provide computing resources to users as services delivered via the internet. The difference between them is that they deliver different amounts or types of such components. In particular, IaaS delivers cloud computing infrastructure, such as servers, networking and storage, while PaaS offers infrastructure, software and middleware as a single framework for building and deploying applications. SaaS provides access to applications.