The development stage of cloud computing, someone finally explained it clearly

Public cloud is the earliest form of cloud computing, and it is also the ultimate form expected by cloud vendors. A public cloud is a cloud computing model in which users connect to a third-party platform to provide shared services and enjoy shared resource services.
The public cloud is not limited to the provision of external services by infrastructure, but also provides external services with platforms, software and data as a new mode of public cloud, namely IaaS (Infrastructure as a Service), PaaS (Platform as a Service), SaaS (Software as a Service), DaaS (Data as a Service).
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