The tremendous advancement of smart devices, wearable computing, large-scale wireless sensor networks, and the Internet of Things (IoT) have significantly impacted day-to-day life. The digital revolution in the IoT has produced a paradigm shift in academia and industries with the generation of an unprecedented amount of data. The IoT paradigm paves the way for the automatic world that interconnects many objects via the Internet to automate certain tasks. To ensure real-time processing, federated and collaborative access to the fog devices nearby, and privacy of data analysis and storage, the research on fog computing has emerged compared to cloud computing. Fog computing extends cloud computing to the edge of the network by providing the data, storage, analysis, computation, and application services closer to the end-users. In order to tackle the research constraints such as cloud reachability, privacy, storage and processing offloading, application latency, and trust, focusing on fog computing researchers has become crucial. Fog computing provides unprecedented opportunities for applications such as real-time navigation, e-health service, manufacturing, and critical infrastructure control.