Short answers, pulled from the story.
The Telharmonium was a massive machine that filled concert halls with sound generated entirely by electricity at the turn of the 20th century. This late 19th-century instrument used rotating shafts and tone wheels to create musical notes without any acoustic source like strings or air columns.
On the 5th of October 1948, Pierre Schaeffer broadcast Etude aux chemins de fer marking the beginning of studio realizations where edited collages of everyday noise became the foundation of electronic composition. He employed a disc cutting lathe, four turntables, a four-channel mixer, filters, an echo chamber, and a mobile recording unit to construct these sound pieces.
Wendy Carlos released Switched-On Bach in 1968 which is a bestselling album of Bach compositions arranged for Moog synthesizer that won three Grammy Awards including Best Classical Album. This record triggered a craze for synthesizer music by demonstrating that complex classical works could be performed entirely on electronic instruments.
By 1951, RTF established the first studio for electronic music production in Paris which later evolved into the Groupe de Recherches de Musique Concrète. The WDR Cologne studio officially opened its doors as what would become the most famous electronic music facility in the world in 1953.
Kraftwerk released albums such as Trans-Europe Express between 1977 and 1981 which influenced subgenres of electronic music across Europe. Gary Numan achieved success with his solo debut album The Pleasure Principle and single Cars in 1979 establishing synth-pop as a dominant force.