Discuss the architectural differences between Infrastructure as a Service (IaaS), Platform as a Service (PaaS), and Software as a Service (SaaS) in cloud computing.

IaaS provides virtualized computing resources over the internet, allowing users to run any operating system or application without the need for physical hardware. PaaS offers a platform allowing customers to develop, run, and manage applications without the complexity of building and maintaining the infrastructure. SaaS delivers software applications over the internet, eliminating the need for installations and maintenance by the user.