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      1 Latency constraints. The fog shares the same fundamental characteristics as the cloud in being able to perform different computational tasks closer to the end-user, making it ideal for latency-sensitive applications for which their requirements are too stringent for deployment in the cloud.

      2 Network bandwidth constraints. Since the fog offers the possibility of performing data processing tasks closer to the edge of the network, lowering in the process the amount of raw data sent to the cloud, it is the perfect device to apply data analytics to obtain fast responses and send to the cloud for storage purposes only filtered data.

      3 Resource constrained devices. Fog computing can perform computational tasks for constrained edge devices like smartphones and sensors. By offloading parts of the application from such constrained devices to nearby fog nodes, the energy consumption and life-cycle cost are decreased.

      4 Increased availability. Another important aspect of fog computing represents the possibility of operating autonomously without reliable network connectivity to the cloud, increasing the availability of an application.

      5 Better security and privacy. A fog device can process the private data locally without sending it to the cloud for further processing, ensuring better privacy and offering total control of collected data to the user. Furthermore, such devices can increase security as well, being able to perform a wide range of security functions, manage and update the security credential of constrained devices and monitor the security status of nearby devices.

       Heterogeneous physical resources. Fog nodes are heterogeneous devices deployed on different components, such as edge routers, access points, and high-end servers. Each component has a different set of characteristics (i.e. RAM and storage) that enables a new set of functionalities. This platform can run on multiple OSes and software applications, deriving a wide range of hardware and software capabilities.

       Fog abstraction layer. The fog abstraction layer consists of multiple generic application programming interfaces (APIs) enabling monitoring and controlling available physical resources like CPU, memory, energy, and network. This layer has the role of making accessible the uniform and programmable interface for seamless resource management and control. Furthermore, using generic APIs, it supports virtualization by monitoring and managing multiple hypervisors and OSes on a single machine with the purpose of improving resource utilization. Using virtualization enables the possibility of having multitenancy by supporting security, privacy, and isolation policies to ensure the isolation of different tenants on the same machine.

       Fog service orchestration layer. The fog service orchestration layer has a distributed functionality and provides dynamic and policy-based management of fog services. This layer has to manage a diverse number of fog nodes capabilities; thus, a set of new technologies and components are introduced to aid this process. One of these components is a software agent called foglet capable of performing the orchestration functionality by analyzing the deployed services on the current fog node and its physical health. Other components are a distributed database that stores policies and resource metadata, a scalable communication bus to send control messages for resource management, and a distributed policy engine that has a single global view and can perform local changes on each fog node.