Infrastructure as a service (IaaS) is a form of cloud computing that provides virtualized computing resources over the internet. In the IaaS model, the cloud provider manages IT infrastructures such as storage, server and networking resources, and delivers them to subscriber organizations via virtual machines accessible through the internet. IaaS can have many benefits for organizations, such as potentially making workloads faster, easier, more flexible and more cost efficient.

Organizations choose IaaS because it is often easier, faster and more cost-efficient to operate a workload without having to buy, manage and support the underlying infrastructure. With IaaS, a business can simply rent or lease that infrastructure from another business.

Platform as a service (PaaS) is a complete development and deployment environment in the cloud, with resources that enable you to deliver everything from simple cloud-based apps to sophisticated, cloud-enabled enterprise applications. You purchase the resources you need from a cloud service provider on a pay-as-you-go basis and access them over a secure Internet connection.

Like IaaS, PaaS includes infrastructure—servers, storage and networking—but also middleware, development tools, business intelligence (BI) services, database management systems and more. PaaS is designed to support the complete web application lifecycle: building, testing, deploying, managing and updating.

PaaS allows you to avoid the expense and complexity of buying and managing software licenses, the underlying application infrastructure and middleware, container orchestrators such as Kubernetes or the development tools and other resources. You manage the applications and services you develop and the cloud service provider typically manages everything else.

Software-as–a-Service (SaaS) model allows to provide software application as a service to the end users. It refers to a software that is deployed on a host service and is accessible via Internet.

Because of the web delivery model, SaaS eliminates the need to install and run applications on individual computers. With SaaS, it’s easy for enterprises to streamline their maintenance and support, because everything can be managed by vendors: applications, runtime, data, middleware, OSes, virtualization, servers, storage and networking.

Function-as-a-Service, or FaaS, a cloud computing service that makes it easier for cloud application developers to build, compute, run, and manage application packages as functions without having to maintain their own infrastructure.

A function is essentially a microservice that can only perform one action in response to an event. Developers using FaaS have access to a platform that allows them to execute the code for their applications. With FaaS, the provider will spin up a server when a function is triggered. It will execute the function, then shut down the server.

Without having to manage servers and by only paying for what you need, you have the time and the resources to focus on your business and the application itself, rather than the infrastructure supporting it.

The fundamental difference between FaaS and SaaS lies in how the two cloud services are applied. While FaaS operates in the microservices of the application landscape and is limited to simple functions, Software as a Service provides users with extensive applications.