Infrastructure as a Service (IaaS) provides virtualized computing resources over the internet. In an IaaS model, the cloud provider manages the physical hardware, while the user manages the virtual resources, such as virtual machines, storage, and networks. PaaS also provides hardware and software tools over the internet, but it goes a step further by also providing a platform on which software can be developed and deployed. SaaS delivers fully functional applications to users. Managed services provide specific services, such as databases or load balancing, with both hardware and software management.