This document summarizes and compares different anti-collision protocols used in RFID systems to address the problem of tag collisions when multiple tags respond simultaneously to a reader. It describes Pure ALOHA, Query Tree, and Multi-Slotted protocols, and evaluates their performance in terms of energy conservation based on simulations. The Multi-Slotted scheme showed the best performance with increased tag numbers, as it reduced energy consumption at both the reader and active tags compared to Pure ALOHA and Query Tree protocols.