Cloud computing is a popular technology in the IT world. After internet, it is the biggest thing for IT world. Cloud computing uses the Internet for performing the task on the computer and it is the next-generation architecture of IT Industry. It is related to different technologies and the convergence of various technologies has emerged to be called as cloud computing. It places the application software and databases to the huge data centers, where the supervision of the data and services may not be fully trusted. This unique attribute poses many new security challenges which have not been well understood.