In the field of IT, cloud computing introduces a new era. Almost every part of the IT depends on this cloud computing. It is the latest technique of providing computational resources as a service. It reduces many hurdles in the field of IT. This technology allows for much more efficient computing by centralizing data storage, processing and bandwidth. The popularity of cloud computing is increasing day by day. The main theme of this paper is to show some important features of cloud computing, its deployment model and some of its dark sides. This paper is prepared based on theoretical research on many literatures about this topic and duration was over a few months.