Fog Computing (FC) is a system that connects cloud computing (CC) with the Internet of Things (IoT). It contributes to easier data transfer between cloud and IoT servers as it makes them closer to each other. FC effectively replaces the services, such as applications and information, at or near the cloud. This limits the bandwidth consumption, decreases delay and facilitates maximum network reliability since the data must not be transmitted to its intended destination or travel long distances. While Software Defined Networking (SDN) is a network engineering technique that permits network control and 'programming' through software applications in an intelligent and centralized way. It is a technology that provides greater programming and flexibility for networks by the separation of the control plane from the data plane. The software-based networks will respond to changes effectively in CC. The SDN presidency increases the efficiency of network setup and enhances network performance and reporting. To improve network efficiency, SDN can be built into FC. In this paper, we first defined FC and touched on its architecture and benefits, relying on the sources of previous studies. Secondly, we defined SDN and explained its components in detail with its method of operation, its benefits, and its impact on networks, and then we presented the method of combining the SDN with FC and the benefits of that. Finally, after relying on a large number of previous researches, we presented some applications that use these two methods together. The results were all indicating improvement in the work of networks in the various applications that were integrated between SDN and FC.