  Edge computing is an emerging concept based on distributing computing,
storage, and control services closer to end network nodes. Edge computing lies
at the heart of the fifth generation (5G) wireless systems and beyond. While
current state-of-the-art networks communicate, compute, and process data in a
centralized manner (at the cloud), for latency and compute-centric
applications, both radio access and computational resources must be brought
closer to the edge, harnessing the availability of computing and
storage-enabled small cell base stations in proximity to the end devices.
Furthermore, the network infrastructure must enable a distributed edge
decision-making service that learns to adapt to the network dynamics with
minimal latency and optimize network deployment and operation accordingly. This
article will provide a fresh look to the concept of edge computing by first
discussing the applications that the network edge must provide, with a special
emphasis on the ensuing challenges in enabling ultra-reliable and low-latency
edge computing services for mission-critical applications such as virtual
reality (VR), vehicle-to-everything (V2X), edge artificial intelligence (AI),
and so forth. Furthermore, several case studies where the edge is key are
explored followed by insights and prospect for future work.
