In today's world, Light Emitting Diodes (LEDs) have become an integral part of our daily lives, illuminating everything from homes to digital displays. Understanding the fundamentals of LEDs is crucial for anyone involved in electronics, lighting, or technology. This comprehensive guide will delve into the essential aspects of LEDs, including their history, emission principles, advantages, structure, classification, industry divisions, production processes, and key optoelectronic parameters. By exploring these topics, readers will gain a deeper appreciation for the remarkable capabilities and widespread applications of LEDs. Whether you are a student, an engineer, or simply a curious reader, this article will provide valuable insights into the world of LED technology.