When bass drops are employed in dubstep music, they are usually put in place to emphasize the chorus of a song. Since there are very rarely any lyrics in this genre of music, bass drops give the listeners notice of a returning melody. Dubstep is a very electronic genre of music, and therefore bass drops are generated through the use of long TR-808 kicks.
In techno music, bass drops are usually used to fill the void of a pause or break during a song. Techno artists use an electrically modified kick drum sound to generate the bass drop.
The metal genre's version of this tactic can literally be felt in the chest and head when executed properly. Unlike the other forms of bass drops, metal bands use a dropped-octave tuning of a bass guitar to create the effect. Metal bands most often use bass drops before, during or after breakdowns.
Bass drops in hip-hop music are a combination of the other genres. The drop itself is produced through both a kick drum and a low-octave bass guitar, but is customized via studio machinery to perfect the sound, like dub and techno. It is used more in live performances than it is in recorded tracks as an attempt to liven up the concert experience.