The adoption of the Internet of Things (IoT) demands advances to cope with the large heterogeneity of IoT entities (i.e., systems, applications, and devices). Context information is an essential characteristic of these entities, which can store relevant details about their environments and related events. However, with the integration of different IoT vertical domains, providing isolated context is no longer enough. Sharing the context information is mandatory to have interoperability. Edge computing emerges as a promising approach to help in filling the context sharing gap by minimizing information overhead and reducing network latency. In this sense, this paper defines an Edge-centric Context Sharing Architecture able to make context sharing based on edge-to-fog approach. We also discuss the requirements for context sharing and the related work in the area to make clear the novelty of the architecture.