Sometimes I have an out of body moment where I see myself as an audience member and think about how dumb-looking the whole process is. You sit somewhere. You gape at something and don't monitor your facial expression because you assume no one is observing you, and then often, you clap. It's definitely a cultural tradition, but sometimes it just feels like an instinct. I sometimes find myself clapping at borderline inappropriate times seemingly because it's a reaction my body is volunteering to perform.
Vsauce provides a series of possible explanations from science and history for why we use clapping to express enthusiasm. It's direct, it's democratic, it's homogenous, it's loud, and it's not as revealing as vocalization. We clap at 2200 HZ to 2800HZ (The Clapper detects frequencies within that range) and the loudest clap ever recorded was 113 dB from 2.5 meters away. And the video even covers the secret explanation that we all know to be true: clapping is a way of high-fiving ourselves for something someone else did. Mystery solved.