Disco of course came about in the 70s. It evolved from earlier soul music and groove oriented sounds along with funk, where the beat was paramount over anything else. It was named after Discotheques clubs that only played music for dancing.  Most of the these were gay clubs in and around New York City where DJs hand picked those groove and soul sounds to inspire movement on the dance floor. As with other 70s genres the Disco Music movement started slowly moving in to the mainstream where it received constant FM radio airplay. This began to give it more universal appeal and as a result producers got involved to give the sound more of a pop orientation without necessarily sacrificing the beat. Eventually even some rock and pop artists got involved as well as the music reached its crescendo during late 70s.