Cloud Computing provides computing services like servers, databases, storage, software, networking and so on from anywhere over internet. Here, cloud means the internet. The main purpose of cloud is to provide services on demand. Cloud providers such as Amazon Web Services (AWS), Microsoft Azure or Google Cloud platform (GCP) provides cloud services. Cloud computing allows organizations to quickly and easily adjust their IT resources by scaling them up or down as needed without investing in expensive hardware upgrades or it provides no upfront hardware investment. The main purpose of this paper is to provide knowledge about cloud computing by considering its evolution and earlier research work. The design of cloud computing is considered in detailed which helps to understand the working of cloud. It also covers the current trends or methodology of cloud by which the emerging opportunities and possibilities are known. And the future trends or methodology and challenges of clouds are considered which helps to know why clouds are becoming popular and obstacles that need to be faced and overcome.
