Cloud computing has generated a lot of interest, but what services exist to support this model? In an effort to cut through some of the hype and let you discuss their real benefits and drawbacks, Forrester has defined a taxonomy for understanding cloud computing and IT services delivered over the Internet. Platform-as-a-service (PaaS) refers to externally hosted services that enable and support the entire application life cycle, from creation to production use. As I&O professionals, understanding PaaS (and other cloud services) will let you make smarter choices in provisioning your infrastructure.