With both IaaS and PaaS offerings, organizations have a lot of fine-grained control over the building, configuration, and deployment of infrastructure and applications. With SaaS applications, all of those management pieces are further separated from administrators and users.

SaaS products are fully deployed applications that are updated and managed by the service provider. When using SaaS applications, administrators usually don't have as many configuration tools available to them. The boundaries of what they can manage are well defined by the service provider. SaaS builds on the services offered by the provider. In the following diagram, you can see how now even the delivery of applications is managed by the cloud service provider.

Users need an active internet connection to access these SaaS applications.

In the previous chapter, we identified a few types of cloud services (such as OneDrive and Spotify). These are examples of SaaS applications. As a user of the system, there is no way to control the amount of storage or networking allocated, nor can you update the infrastructure. Users connect to those services using a web browser or application on their devices and can only consume or create within the boundaries that the application allows.

Microsoft 365 is another example of a SaaS application. When users connect to the internet to access email with Microsoft 365, the Exchange Online SaaS application is responding. Microsoft 365 exemplifies the cloud service benefits outlined in the previous chapter: only the exact amount of service required is purchased, and the service provider is responsible for the maintenance of the application and its underlying hardware components. As a subscriber, the fee covers the servers, storage, and networking needed to provide the service. 

While the Microsoft 365 suite is an example of SaaS, each of its constituent applications (Office Online, Power Automate, and Teams) is also an example of SaaS.

Finally, we'll tackle the newest entry in the cloud services scenarios: serverless computing.