Cloud vs on-premises: public, private and hybrid cloud; SaaS, PaaS and IaaS

On-premises (on-prem) means the organization owns and runs the servers, storage and networking in its own building or data center. It controls everything, but it must also buy the hardware up front, power and cool it, patch it and replace it. Cloud computing means using computing resources delivered over a network on demand, typically paid for as you use them, and able to scale up or down quickly.