There are three types of service delivery or cloud computing categories that can be used to divide cloud computing. These categories are shown in the following figure.
Cloud Service Models
Infrastructure as a Service (IaaS): IaaS providers like Amazon Web Services (AWS) offer a virtual server instance, storage, and application programming interfaces (APIs) that let users move workloads to a virtual machine (VM). Users are given a certain amount of storage and can start, stop, access, and change the VM and storage as needed. IaaS providers offer small, medium, large, and extra-large memory- or compute-optimized instances, as well as the ability to customize instances to meet specific workload needs. The IaaS cloud model is the most like a remote data center for business users.
Platform as a Service (PaaS): In the PaaS model, the cloud hosts development tools on its infrastructures. Users access these technologies over the internet through APIs, web portals, and gateway software. PaaS is a platform for making software that can be used by anyone. Once the software is done, many PaaS providers host it. Popular PaaS options include Salesforce's Lightning Platform, AWS Elastic Beanstalk, and Google App Engine.
Software as a Service (SaaS): Most of the time, SaaS refers to Web services. SaaS is a way of getting software applications to users over the internet. Users can access SaaS apps and services from anywhere with a PC or mobile device that can connect to the internet. Through the SaaS model, users can use application software and databases. One example of a SaaS application is Microsoft 365, which is a productivity and email service.