Which cloud computing service model provides customers with virtualized computing infrastructure — such as virtual machines, storage, and networking — while the customer remains responsible for managing the operating system and applications?

IaaS (Infrastructure as a Service) provides fundamental virtualized computing resources — servers, storage, and networking — over the internet, while the customer manages the operating system, middleware, and applications on top of it. SaaS delivers fully managed, ready-to-use software applications. PaaS provides a managed platform, including the OS and runtime, without infrastructure management. FaaS lets developers run individual functions without managing servers at all, and DaaS delivers virtual desktops to end users.