In this study different security and privacy related research papers were studied briefly. Cloud services are used by both larger and smaller scale organizations. Advantages of Cloud computing are huge. But it‘s a global phenomenon that everything in this world has advantages as well as disadvantages. Cloud computing is suffering from severe security threats from user point of view, one can say that lack of security is the only worth mentioning disadvantage of cloud computing. Both the Service providers and the clients must work together to ensure safety and security of cloud and data on clouds. Mutual understanding between service providers and users is extremely necessary for providing better cloud security. In this paper we have identified that security is biggest hurdle in wide acceptance of cloud computing. Users of cloud services are in fear of data loss and privacy. Researchers and IT security professionals must come forward and do more to ensure security and privacy to users. Our study identifies top security concerns of cloud computing, these concerns are Data loss, Leakage of Data, Client‘s trust, User‘s Authentication, Malicious users handling, Wrong usage of Cloud computing and its services,