On-premise IT models require upfront capital expenditures and ongoing operational expenses, while cloud models offer a pay-as-you-go operational expense approach with more flexibility and scalability. Cloud services provide elasticity, redundancy, availability, and the ability to scale resources up or out as needed. There are different cloud deployment models including private, community, public, and hybrid clouds that offer varying levels of control, customization, security, and scale. Common cloud service models are SaaS, PaaS, and IaaS that provide software, platforms, and infrastructure respectively, with vendors managing more of the underlying layers the further left on the spectrum.