What is the definition of cloud computing?

At the upper level, cloud computing can be divided into: IaaS, PaaS, SaaS. IaaS refers to the mode of abstracting physical computing, storage, network and other resources to form software computing, storage, network and other resources to achieve unified management, provide flexible supply and distribution according to demand, and the interconnected data virtual machine is the representative. PaaS refers to middleware, database and other platform software; SaaS refers to the upper application software, such as collaborative SaaS software, financial SaaS software.

Cloud computing is divided into public cloud, industry cloud, private cloud and hybrid cloud, in which telecom enterprises provide all cloud services, and private cloud is to deploy cloud platform in their own data center for their own use. Hybrid cloud can be a mixture of public cloud and private cloud, or a mixture of industry cloud and private cloud, mainly for security considerations. All interconnected data put customer unimportant, non-core, non-secret-related business on the public cloud / industry cloud, and important core secret-related business on the private cloud.