Microsoft 365 is an example of which cloud service model?

Infrastructure as a Service (IaaS) provides virtualized computing resources, but customers are responsible for installing and managing applications and operating systems.

Platform as a Service (PaaS) provides a development and deployment environment for building applications, not a complete, end-user application suite.

Software as a Service (SaaS) provides users with a complete, ready-to-use application managed by a third-party provider over the internet, eliminating the need for customers to manage any underlying infrastructure, platform, or even the application itself. Microsoft 365 fits this model by offering productivity applications and related services accessed via a web browser or client software without requiring customers to install or manage the underlying operating system or servers.