What was Thomas Edison's favorite invention?

Thomas Edison's favorite invention was the phonograph. Edison invented the phonograph in 1877. It was through his efforts to improve the telephone and telegraph that he conceived the idea to record sound on tinfoil-coated cylinders.

According to the Charles Edison Fund, Edison was the first to conceive the idea to record sound for reproduction. His first phonograph was a success. Edison contributed greatly to telecommunications and held over a 1,000 patents in the U.S. and Europe. Interestingly, Edison went deaf later in life due to hearing problems he developed at a young age, which were later exacerbated by an accident.