Cloud Computing is the important buzzword in the today’s world of computer. Cloud is global platform that allows digital information to be stored and distributed at very less cost and very fast to use. In these days since the data is very big in size many users are interested to store their valuable data in the cloud .The application software and databases in cloud computing are moved to the centralized large data centers, where the management of the data and services may not be fully trustworthy. Cloud Computing is scalable, fast, flexible, and cost-effective technology platform for IT enabled services over the internet. There are various advantages of cloud computing but ultimately cloud service users have to put their data over the cloud i.e., third party servers which are not directly controlled by the data owner Data security has consistently been a major issue in information technology In cloud computing in users perspective mainly in government ,industry and business Data security and ivacy protection issues are relevant to both hardware and software in the cloud architecture. Cloud security is becoming a key differentiator and competitive edge between cloud providers. In spite of various benefits that are provided by the cloud computing services, cloud computing service users are very much afraid about the security of their data .So this paper focuses on various issues regarding cloud computing, data security and how cloud provides data integrity, confidentiality, availability over user’s data? How data stored over cloud storage servers will be protected from attackers? Risk management of data present on the Cloud is another challenge. There is a requirement to identify the risks an organization would be taking while hosting data and services on the Cloud. In this paper, we present those issues that are preventing people from adopting the cloud and to minimize risks of these issues.