Computation encounter the new approach of cloud computing which maybe keeps the world and possibly can prepare all the human's necessities. In other words, cloud computing is the subsequent regular step in the evolution of on-demand information technology services and products. The Cloud is a metaphor for the Internet and is a concept for the covered complicated infrastructure; it also depends on sketching in computer network diagrams. In this paper we will focus on concept of cloud computing, cloud deployment models, cloud security challenges encryption and data protection, privacy and security and data management and movement from grid to cloud.