Most days I spend quite a bit of time browsing educational and technical websites. Today, this led me to reading about the early history of transistor radios and transistors.
The transistor was invented in 1947. In many electronic circuits such as in a radio, a transistor could be used in place of a vacuum tube (Wikipedia, n.d.a). The transistor is smaller, much more rugged, has a much longer expected life, and uses much less electric power.