In this paper, we consider blockchain technology that enabledthe existence of digital currency and we investigate Bitcoin cryptocurrency application. This technology nowadays represents a new feature that replaces existing client-server core system on top of some distributed systems with many additional features such as high availability, resistance to alteration, fault tolerance and cost reduction. After overviewing how such technology is working, we highlightthe requirements and benefits related to the security, database and network. We mainly focus on answering the most Bitcoin queries including privacy and double spending. Furthermore, as blockchain has potential applications far beyond bitcoin, we draw future insights where applications based blockchain are provisioned in the market in order to be totally or partially independent of the centralized systems and we provide a questionnaire helping organizations for better using the blockchain feasibilities.