In dance music vocabulary, the ubiquitous ‘drop’ refers to the section of a track where the main melody is introduced, and you can recognise it instantly for the fact that it has the highest energy level in the track.
The drop is preceded by a build-up section and break that has contrasting elements to create tension.
After this section plays out, heavy drums, bass and and the main melodic elements kick in. The drop needs to land as powerfully as it possibly can, and emphasise the theme of the song to its full potential. In order to have maximum impact, a drop needs the right combination of sounds and contrasting elements for it to deliver the goods.