By the mid-80s house was starting to emerge as a genre and Jesse Saunders’ On and On (1984) can be seen as one of the first definitive house records. From the mid-80s more DJs began exploring this sound and various Chicago DJs were producing their own tracks. House became more popular and reached a wider audience, leading to derivative genres such as deep house, electro house and acid house. House music is characterised by a uniform four-on-the-floor beat as well as off-beat hi-hats and a snare backbeat. The music is typically around 120 bpm and a big part of the sound is the use of iconic drum machines such as the Roland TR-808 and synth melodies.