Which concept best describes a cloud model that requires no purchase or operation of hardware and optimizes physical resource usage?

The concept that best describes a cloud model requiring no purchase or operation of hardware while optimizing physical resource usage is serverless computing. This model allows developers to build and run applications without having to manage the underlying infrastructure.

In a serverless architecture, the cloud provider automatically provisions, scales, and manages the servers needed to run the application, which means that users can focus on writing code and deploying applications rather than managing hardware and infrastructure. This optimizes resource usage because it allows for efficient allocation of computing power based on demand. Users only pay for the compute time that they consume, which can lead to significant cost savings and efficient resource utilization.

In comparison, other cloud models may still require some degree of hardware management or upfront costs, such as purchasing virtual machines or employing hybrid strategies that utilize both on-premise and cloud resources. Serverless computing abstracts these complexities, making it the most fitting choice for the described scenario.