Introduction: Rare Earth Elements (REEs) are crucial for advanced technologies in modern society, ranging from electronics to renewable energy and defense. Their increasing demand in critical industries underscores the need for a consistent and sustainable supply. Historically extracted from REE-rich minerals such as bastnäsite and monazite, the search for alternative sources has gained prominence, among these, coal ashes stand out, produced by burning coal to generate energy, ashes contain REEs in relatively low concentrations but with significant potential due to their massive global volume. The importance of ensuring the resilience of the REE supply chain has driven research to extract these elements from coal ashes, diversifying sources and reducing reliance on specific minerals. As technologies advance and REE applications expand, the ability to recover them from unconventional sources like coal ashes could have a sustainable impact on our societies. Research into the extraction and utilization of REEs from ashes is in progress and may enhance supply security. This study highlights the global importance of finding alternative sources of REE, such as coal ash, emphasizing the need to ensure a consistent and sustainable supply of these essential elements.