With the rate of an increasing number of devices connected to the internet and rapidly increasing traffic demands, there is a need to develop a mechanism that should be able to cope with the challenges currently being faced by various Wide Area Network (WAN). SD-WAN (Software-Defined- Wide Area Network) is a new WAN technology that incorporates the features of Software Defined Networking (SDN). With its enormous benefits and simple working principle of separating the control plane and data, the plane produces many new opportunities that further diminish the various limitations of traditional WAN technologies such as flexibility, cost, and inefficiencies. This paper aims to provide an overview of SD-WAN research and technologies by comparing it with traditional methods of WAN technologies. It will help various researchers and industrialists to have an overview of this new technology which is an area of high interest over the upcoming year.