There are some definitions of cloud computing but it can be defined as utilization of personal computers, servers and softwares in one cluster for approaches to the use of shared computing resources. Nowadays the applications of cloud computing are rapidly increasing because of its merits on economic aspect, connectivity convenience, storage space and so on. The main objective of this paper is to find an effective methodology as an initial stage for applications of cloud computing in a real life. Therefore this paper addresses worldwide reviews on cloud computing.