Which of the following cloud service models focuses primarily on software delivery over the internet?

The focus on software delivery over the internet is a defining characteristic of the Software as a Service (SaaS) model. In this model, applications are hosted in the cloud and made available to users via a web browser. Users do not need to install or maintain any hardware or software on their local machines; instead, they access the software remotely, usually through a subscription-based model.

SaaS allows businesses and individuals to use applications without the complexities associated with maintaining the infrastructure or development environment. Services like email, customer relationship management (CRM), and collaboration tools are typical examples of SaaS offerings, allowing users to leverage software without the need for in-depth IT management or technical knowledge.

In contrast, other models such as Platform as a Service (PaaS) provide a platform for developers to build and deploy applications, while Infrastructure as a Service (IaaS) offers virtualized computing resources over the internet. Function as a Service (FaaS) involves executing code in response to events without the need to manage the underlying infrastructure. These models serve different needs and use cases, but they do not primarily focus on software delivery in the way SaaS does.