Which model allows customers to use software applications hosted on the cloud without handling the underlying infrastructure?

The model that allows customers to use software applications hosted on the cloud without dealing with the underlying infrastructure is Software as a Service (SaaS). In this model, the service provider manages everything from the infrastructure to the application itself, meaning customers can access and use the software over the internet without needing to worry about server maintenance, network configuration, or the installation and management of software on their personal devices.

SaaS enables users to leverage applications such as email, customer relationship management (CRM), and collaboration tools seamlessly while being primarily responsible for data input and usage. This model is highly beneficial for businesses as it reduces IT overhead and provides immediate access to the latest software features without the need for upfront investments in hardware or ongoing maintenance efforts.

Other models like Infrastructure as a Service (IaaS) and Platform as a Service (PaaS) do require more involvement from the customer in terms of managing infrastructure or building and deploying applications, respectively. Function as a Service (FaaS) is primarily focused on executing code in response to events, which also does not align with simply using applications as users would in a SaaS environment. Thus, SaaS stands out as the ideal choice for using software applications in a cloud environment without infrastructure concerns.