介绍了云计算的发展历史和应用场景, 比较了现有的云计算的定义并给出了新的定义, 以谷歌的云计算技术为例, 总结了云计算的关键技术。-Describes the history and development of cloud computing scenarios, comparing the existing definitions of cloud computing and gives a new definition to Google' s cloud computing technology, for example, summarizes the key technology of cloud computing.