In recent years, cloud computing has been an emerging computing model in the IT industry. Many big companies are throwing resources into it. It provides efficient computing by centralizing storage, memory processing and bandwidth. Adopting cloud computing can result in both positive and negative effects on data security. This paper presents a study about the challenges of cloud computing. It highlights the different types of risks and how their existence can affect the cloud users. There are numerous contests are being raised for espousal of the cloud including data security, availability and confidentiality.