Cloud Infrastructure is the collection of hardware and software elements such as computing power, networking, storage, and virtualization resources needed to enable cloud computing. Cloud infrastructure types usually also include a user interface (UI) for managing these virtual resources.
Infrastructure as a Service, or IaaS, is a prominent and accessible example of this model. With IaaS, a team or enterprise acquires the computing infrastructure it needs over the Internet, including computing power (whether on physical or, more likely, virtual machines), storage, and plenty of related needs such as load balancers and firewalls. They do this in lieu of provisioning and managing their own physical infrastructure. Instead, they lease the resources they need from the IaaS provider.
While this is a well-known example, cloud infrastructure, or cloud architecture, encompasses a larger range of platforms and environments, including private and hybrid clouds.