After the discovery of the electron, the field of electronics really began to blossom. The first key development, between about 1902 and 1906, was the vacuum tube. The vacuum tube could do something new, it could amplify an electrical input or signal. Imagine how important this was to the development the radio. One challenge for radio technology of was the need to receive faint radio-wave signal and convert it into a a strong enough electrical signal able to produce sound that could be heard easily by the listener. The vacuum tube filled this need.