Cloud computing is a mode of increasing, using and delivering related services based on the Internet, which usually involves providing dynamically scalable and often virtualized resources through the Internet. Cloud is a metaphor of network and internet. In the past, cloud was often used to represent telecommunication networks, and later it was also used to represent the abstraction of the Internet and the underlying infrastructure. In a narrow sense, cloud computing refers to the delivery and use of IT infrastructure, and refers to obtaining the required resources in an on-demand and scalable way through the network; Cloud computing in a broad sense refers to the delivery and use of services, and refers to obtaining the required services in an on-demand and extensible way through the network. The service can be related to IT and software, Internet or other services. It means that computing power can also be circulated as a commodity through the Internet.