Pushing computation, control and storage into the "cloud" has been a key trend in networking in the past decade. Over-dependence on the cloud, however, indicates that availability and fault tolerance issues in the cloud would directly impact millions of end-users. Indeed, the cloud is now "descending" to the network edge and often diffused among the client devices in both mobile and wireline networks. The cloud is becoming the "fog." Empowered by the latest chips, radios, and sensors, each client device today is powerful in computation, in storage, in sensing and in communication. Yet client devices are still limited in battery power, global view of the network, and mobility support. Most interestingly, the collection of many clients in a crowd presents a highly distributed, under-organized, and possibly dense network. Further, wireless networks is increasingly used locally, e.g. intra-building, intra-vehicle, and personal body-area networks; and data generated locally is increasingly consumed locally. Fog Network presents an architecture that uses one or a collaborative multitude of end-user clients or near-user edge devices to carry out storage, communication, computation, and control in a network. It is an architecture that will support the Internet of Things, heterogeneous 5G mobile services, and home and personal area networks. Fog Networking leverages past experience in sensor networks, P2P and MANET research, and incorporates the latest advances in devices, network systems, and data science to reshape the "balance of power" in the ecosystem of computing and networking.