This review provides an extensive overview of the fundamentals, historical development, and current applications of Light-Emitting Diodes (LEDs), with a focus on ultraviolet (UV) LEDs and their use in microbial deactivation. The paper discusses the evolution of LED efficiency for UV, blue, green, and red LEDs, highlighting key advancements in material selection, design, and fabrication techniques. It also explores the diverse applications of LEDs in solid-state lighting, display technology, and microbial disinfection, emphasizing their potential in water purification and surface disinfection. The review outlines current trends and future prospects in lighting and display technology, with a particular emphasis on the integration of UV LEDs with emerging technologies such as sensors, solar power, and artificial intelligence for enhanced disinfection practices. The paper also presents a prospective design for a solar-powered UV LED disinfection system. The authors conclude that LED efficiency has continuously increased since their invention, and there is a growing demand for LED lighting and display applications. The integration of UV LEDs with advanced technologies offers promising opportunities for high-precision and effective microbial disinfection. The review underscores the importance of ongoing research in material science, device engineering, and manufacturing techniques to further improve LED efficiency and expand their applications in various fields.This review provides an extensive overview of the fundamentals, historical development, and current applications of Light-Emitting Diodes (LEDs), with a focus on ultraviolet (UV) LEDs and their use in microbial deactivation. The paper discusses the evolution of LED efficiency for UV, blue, green, and red LEDs, highlighting key advancements in material selection, design, and fabrication techniques. It also explores the diverse applications of LEDs in solid-state lighting, display technology, and microbial disinfection, emphasizing their potential in water purification and surface disinfection. The review outlines current trends and future prospects in lighting and display technology, with a particular emphasis on the integration of UV LEDs with emerging technologies such as sensors, solar power, and artificial intelligence for enhanced disinfection practices. The paper also presents a prospective design for a solar-powered UV LED disinfection system. The authors conclude that LED efficiency has continuously increased since their invention, and there is a growing demand for LED lighting and display applications. The integration of UV LEDs with advanced technologies offers promising opportunities for high-precision and effective microbial disinfection. The review underscores the importance of ongoing research in material science, device engineering, and manufacturing techniques to further improve LED efficiency and expand their applications in various fields.