I was helping out at an Azure Fundamentals training day event and one question that came up a lot was could you provide some examples of IaaS, PaaS, SaaS, so I thought I'd share my take on the answer to that questions.
Infrastructure as a Service
Infrastructure as a Service (IaaS) refers to components such as compute, networking and storage. On prem IaaS would be your virtual machine infrastructure, so something hosted on Hyper-V or VMware for example.
On prem you have to take care of every aspect of it though from networking to the applications. IaaS in the cloud you manage from the operating system level up to the application level. The cloud vendor looks after the networking to virtulisation layer.
Creating a virtual machine (or server) within Azure is an example of IaaS.
Platform as a Service
Platform as a Service (PaaS) allows you to take advantage of technology but not have to worry about the complexity of building or maintaining the necessary infrastructure. One of my favourite examples of PaaS within Azure is the Web App offering, you can host your website on Azure without having to maintain the infrastructure, just point the Web App towards your ebsite code and Azure will make it available for visitors.
Software as a Service
Software as a Service (SaaS) is when a third party provider hows the software you wish to use and you can access it via the Internet. Often SaaS offerings are usually only valid with a relevant subscription and they are easily scalable with your needs.
One great example of SaaS is Microsoft 365, you can host your email online and not need to have any of that infrastructure in place on prem, which in the past I've seen be about 3 or 4, if not more servers. And you don't have to care about the operating system updates, hardware failures, all of that is taken care of within your subscription fee.