In this paper, the concept of cloud computing has been studied. The service provider must ensure that the infrastructure and applications are protected and must take actions to reinforce user’s application and use strong passwords and authentication measures. In the first part, a brief introduction to the cloud computing has been given. It includes a definition of cloud computing given by NIST and other scholars. In the next section, the architecture and various service models, as well as deployment models provided by cloud computing, has been discussed. This is followed by the working of the cloud which includes the concept of virtualization. Then the light has been put on its major application areas. In the next part, its advantages and disadvantages have been highlighted.