In modern communication systems, relay nodes play a pivotal role in enhancing signal coverage, improving communication quality, and extending network reach. These relay nodes, positioned between the transmitter and receiver, facilitate the efficient transfer of data by forwarding the signals, especially in scenarios where direct communication may be compromised due to obstacles, interference, or distance. To ensure optimal operation of relay nodes, it is crucial to evaluate their performance through various metrics, known as Relay Performance Metrics. These metrics serve as indicators of the efficiency, reliability, and overall functionality of relay networks. In this article, we will explore the most commonly used relay performance metrics and discuss their significance in modern communication networks.