IT world is changing. Evolution of cloud computing in recent past has brought drastic change in era of IT field. Major advantage of cloud computing is that the hardware need not to be upgraded as Cloud Services provides everything of demand basis. Consuming electricity is the best example by which cloud computing can be explained, just pay for whatever the users’ used. In this paper, the authors present a comparative study of leading cloud providers such as Amazon Cloud Services, Rackspace powered by OpenStack and other open source Cloud providers. Further discussing about how to implement OpenStack or just trying out by Devstack and Trystack just for testing purpose and at last covering releases and recent work going on in OpenStack.