IaaS > Paas > SaaS

Before cloud providers such as Amazon, Google, Microsoft, Linode and others, if a business wanted to provide an online service or product, they had to manage everything end to end themselves.

that is your organisation would have to purchase, setup and maintain your entire infrastructure stack, it could look something link this

It's a lot of upfront costs, a lot of specialised expertise not just to configure, but to maintain, keep secure and be ready to replace. Running your own infrastructure on premise is not just expensive from a capital cost perspective, but it's operational costs are extremely high as well. This is why the cloud went from relative obscurity in the mid 2000s, to business ubiquity today. 

By leveraging cloud services, you can eliminate your capital and greatly reduce your operational costs. there are three main services that cloud providers offer they are:

Infrastructure as a Service (IaaS) can help a business undergo digital transformation by providing access to virtualized computing resources, such as servers, storage, and networking. With IaaS, a business can quickly scale its IT infrastructure without having to invest in expensive physical hardware. This allows the business to focus on developing and deploying innovative digital products and services, without having to worry about managing the underlying infrastructure.

Platform as a Service (PaaS) offers a complete development and deployment platform for applications. It enables businesses to build, test, and deploy applications on a cloud-based infrastructure, without having to worry about the underlying infrastructure management. This allows businesses to focus on their core competencies and drive innovation, rather than spending time and resources on managing the IT infrastructure. PaaS also provides businesses with the ability to rapidly launch new digital products and services, which is crucial for companies undergoing digital transformation.

Software as a Service (SaaS) provides a way for businesses to access software applications over the internet, rather than having to install and run them on their own computers. SaaS can help businesses achieve digital transformation by providing access to a wide range of applications, from customer relationship management (CRM) systems to enterprise resource planning (ERP) solutions, without having to invest in expensive software licenses and hardware. With SaaS, businesses can focus on driving innovation and delivering value to their customers, while the SaaS provider takes care of software updates, security, and maintenance.

A simple way to think of it is like this:

• Infrastructure (IaaS): is the hardware that your application or service runs on.
• Platform (PaaS): is the software that your application needs to run
• Software (Saas): is the actual application or service.

Here's a simplistic representation.