system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What makes the strong 'click!' sound when you snap your fingers?

What on the finger's surface causes it to make such a strong sound?
gpt
The sound doesn't actually come from your fingers themselves.  The sound you hear is your finger hitting your palm just under your thumb - it's like a small version of clapping.

The reason you need to 'snap' to get it is to get the finger moving fast enough to make noise.  You build up pressure against the thumb, and then the finger slaps into your palm fast enough to make noise.