Well as far as I read:
Lee Deforest invented space telegraphy, the triode amplifier and the Audion. In the early 1900s, the great requirement for further development of radio was an efficient and delicate detector of electromagnetic radiation. Lee De Forest provided that detector. It made it possible to amplify the radio frequency signal picked up by the antenna before application to the receiver detector; thus, much weaker signals could be utilized than had previously been possible. De Forest was also the person who first used the word "radio".
The result of Lee DeForest's work was the invention of amplitude-modulated or AM radio that allowed for a multitude of radio stations. The earlier spark-gap transmitters did not allow for this.
Lee Deforest invented space telegraphy, the triode amplifier and the Audion. In the early 1900s, the great requirement for further development of radio was an efficient and delicate detector of electromagnetic radiation. Lee De Forest provided that detector. It made it possible to amplify the radio frequency signal picked up by the antenna before application to the receiver detector; thus, much weaker signals could be utilized than had previously been possible. De Forest was also the person who first used the word "radio".
The result of Lee DeForest's work was the invention of amplitude-modulated or AM radio that allowed for a multitude of radio stations. The earlier spark-gap transmitters did not allow for this.