Thomas Edison was a prolific inventor and entrepreneur who is considered important for many reasons, including:
Research and development
Edison's approach to invention, which involved staffing his laboratory with scientists engaged in basic research, was a novel concept in the United States and continues to influence modern research-and-development laboratories. 
Business acumen
Edison established the Edison General Electric Company (now known as General Electric) in 1889, merging his various businesses to create a powerful corporation. 
Light bulb
Edison's invention of the practical incandescent light bulb in 1879 transformed the way people lived and laid the groundwork for the modern electric utility industry. 
Phonograph
Edison's 1877 invention of the phonograph, which allowed for the recording and playback of sound, revolutionized the music industry and paved the way for modern audio technology. 
Motion picture
Edison played a key role in the development of the motion picture industry, inventing the kinetoscope and working on early film cameras. 
Edison held over 1,000 patents in various fields, including telegraphy, motion pictures, and storage batteries.