With the proliferation of Internet of things (IoT) and the burgeoning of 4G/5G network, we have seen the dawning of the IoE (Internet of everything) era, where there will be a huge volume of data generated by things that are immersed in our daily life, and hundreds of applications will be deployed at the edge to consume these data. Cloud computing as the de facto centralized big data processing platform is not efficient enough to support these applications emerging in IoE era, i.e., 1) the computing capacity available in the centralized cloud cannot keep up with the explosive growing computational needs of massive data generated at the edge of the network; 2) longer user-perceived latency caused by the data movement between the edge and the cloud;3) privacy and security concerns from data owners in the edge; 4) energy constraints of edge devices. These issues in the centralized big data processing era have pushed the horizon of a new computing paradigm, edge computing, which calls for processing the data at the edge of the network. Leveraging the power of cloud computing, edge computing has the potential to address the limitation of computing capability, the concerns of response time requirement, bandwidth cost saving, data safety and privacy, as well as battery life constraint. “Edge” in edge computing is defined as any computing and network resources along the path between data sources and cloud data centers. In this paper, we introduce the definition of edge computing, followed by several case studies, ranging from cloud offloading to smart home and city, as well as collaborative edge to materialize the concept of edge computing. Finally, we present several challenges and opportunities in the field of edge computing, and hope this paper will gain attention from the community and inspire more research in this direction.