This paper provides a comprehensive literature review on the fundamentals and historical development of Light-Emitting Diodes (LEDs), focusing on material selection, design, and modifications to enhance light output. It traces the evolution of efficiency in UV, blue, green, and red LEDs, examining their diverse applications in solid-state lighting, display technology, and microbial deactivation. The review highlights current trends and future prospects in lighting and display technology, emphasizing the integration of UV LEDs with advanced technologies like sensors, solar power, IoT devices, and artificial intelligence for precise and effective disinfection. The paper also discusses the challenges and advancements in material selection and device design, particularly in UV LEDs, and presents a detailed analysis of microbial disinfection using UV LEDs. Additionally, it explores the potential of solar-powered UV LED systems for water purification and surface disinfection. The primary objective is to organize and synthesize key information from the literature, offering a concise overview of LED applications and their future potential.This paper provides a comprehensive literature review on the fundamentals and historical development of Light-Emitting Diodes (LEDs), focusing on material selection, design, and modifications to enhance light output. It traces the evolution of efficiency in UV, blue, green, and red LEDs, examining their diverse applications in solid-state lighting, display technology, and microbial deactivation. The review highlights current trends and future prospects in lighting and display technology, emphasizing the integration of UV LEDs with advanced technologies like sensors, solar power, IoT devices, and artificial intelligence for precise and effective disinfection. The paper also discusses the challenges and advancements in material selection and device design, particularly in UV LEDs, and presents a detailed analysis of microbial disinfection using UV LEDs. Additionally, it explores the potential of solar-powered UV LED systems for water purification and surface disinfection. The primary objective is to organize and synthesize key information from the literature, offering a concise overview of LED applications and their future potential.