A business uses a cloud service where the provider manages the OS, security updates, and runtime environment while the customer focuses on development. Which cloud service model is being used?

SaaS delivers software applications over the internet, eliminating the need for installation and management by the user. While users can access and utilize the software, they do not manage the underlying infrastructure, runtime, or security, which distinguishes it from PaaS where development and environment management are involved.

Public cloud refers to computing resources provided over the internet by third-party providers, accessible to anyone. While PaaS can be delivered via a public cloud, the term itself does not specify the management of the OS, security, or runtime environment, which is essential to identify the specific service model in use.

IaaS offers virtualized computing resources over the internet, allowing users to manage their operating systems, applications, and middleware. In this model, customers are responsible for managing the OS and updates, which contrasts with the PaaS model where these responsibilities lie with the provider.