[t]he cloud infrastructure . . . provisioned for open use by the general public. It may be owned, managed, and operated by a business, academic, or government organization, or some combination of them. It exists on the premises of the CSP and/or its suppliers.
[In p]ublic clouds . . . services are offered to individuals and organisations who want to retain elasticity and accountability without absorbing the full costs of in-house infrastructures. Public cloud users are by default treated as untrustworthy.