This document summarizes and compares different RFID-based anti-counterfeiting systems. It discusses four main approaches: 1) Using physical unclonable functions (PUFs) or chipless RFID tags that are unique and difficult to clone; 2) Track and trace systems that record the product flow from manufacturer to retailer to authenticate products; 3) Distance bounding protocols that use broadcast and collisions to identify cloned tags without complex cryptography; 4) Each approach has advantages and disadvantages for resolving counterfeiting issues using RFID tags in supply chains. The document provides examples and evaluations of techniques within each category.