This document provides an overview of key concepts related to Frame Relay networks, including the User Network Interface (UNI) and Network-to-Network Interface (NNI) that define connections between user devices and networks. It describes common connection types like Permanent Virtual Circuits (PVCs) and Switch Virtual Circuits (SVCs), as well as how Frame Relay networks support mesh networking topologies with virtual private networks (VPNs). The document concludes by noting that Frame Relay involves less network processing than earlier protocols like X.25.