Cloud Computing is a promising and emerging technology that is rapidly being adopted by many IT companies due to a number of benefits that it provides, such as large storage space, low investment cost, virtualization, resource sharing, etc. Users are able to store a vast amount of data and information in the cloud and access it from anywhere, anytime on a pay-per-use basis. Many users are able to share the data and the resources stored in the cloud. Hence, there arises a need to provide access to the data to only those users who are authorized to access it. This can be done by enforcing access control schemes which allow only the authenticated and authorized users to access the data and deny access to unauthorized users. In this paper, a comprehensive review of all the existing access control schemes has been discussed along with the analysis of these schemes.