Which cloud service model offers software to subscribers on-demand over the internet?

• A. Platform as a Service (PaaS)
• B. Software as a Service (SaaS)
• C. Infrastructure as a Service (IaaS)
• D. Identity as a Service (IDaaS)

Answer: (B)

Software as a service delivers fully functional software applications over the internet on demand. Subscribers access the software through a web browser or thin client, while the vendor hosts, maintains, scales, and updates the application. This model removes the need to install or manage the software locally or handle underlying infrastructure, making it easy to start using quickly and pay as you go. Examples include Google Workspace, Salesforce, and Microsoft 365. Other cloud service models focus on different layers: platform as a service provides a development platform on top of infrastructure, letting you build and deploy apps; infrastructure as a service offers raw compute, storage, and networking resources; identity as a service specializes in managing user identities and access rather than delivering general software.