This is what we found on Wikipedia regarding the Hedex:

Electronic dance music (EDM), also referred to as dance music or club music, is a broad range of percussive electronic music genres originally made for nightclubs, raves, and festivals. It is generally produced for playback by DJs who create seamless selections of tracks, called a DJ mix, by segueing from one recording to another. EDM producers also perform their music live in a concert or festival setting in what is sometimes called a live PA. Since its inception EDM has expanded to include a wide range of subgenres.

During the late 1980s to early 1990s, following the emergence of electronic music instruments, rave culture, pirate radio, party crews, underground festivals, and an upsurge of interest in club culture, EDM achieved mainstream popularity in Europe and Japan. However, rave culture was not as broadly popular in the United States; it was not typically seen outside of the regional scenes in New York City, Florida, the Midwest, and California. Although the pioneer genres of electro, Chicago house and Detroit techno were influential both in Europe and the United States, mainstream media outlets and the record industry in the United States remained openly hostile to it until the 1990s and beyond. There was also a perceived association between EDM and drug culture, which led governments at state and city levels to enact laws and policies intended to halt the spread of rave culture.

Subsequently, in the new millennium, the popularity of EDM increased globally, particularly in the United States and Australia. By the early 2010s, the term "electronic dance music" and the initialism "EDM" was being pushed by the American music industry and music press in an effort to rebrand American rave culture. Despite the industry's attempt to create a specific EDM brand, the name remains in use as an umbrella term for multiple genres, including dance-pop, house, techno, electro and trance, as well as their respective subgenres, which all predate the name.