In cloud computing, physical servers and disk systems are infrastructure provided by a "Cloud Service Providers" (CSP). This infrastructure usually appears to be virtual in nature and may be allocated and freed programmatically, giving the user virtually unlimited access to compute and storage resources.

This infrastructure is provided as a service wherein the use of resources, including bandwidth, compute time, and storage is billed to the user. The term for such services is, thus, Infrastructure-as-a-Service.

An example of a CSP (or IaaS) is Amazon Web Services.

See Also: Cloud Computing, Platform-as-a-Service, Software-as-a-Service