system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do bongs work?

I know how to use them, please don't explain how to use them. I just want to understand what's happening when you're using a bong.
gpt
The smoke has some of the tars filtered out and is cooled somewhat when it's drawn through the water.  That's the whole point of using a bong or other waterpipe.  You apply suction (negative pressure) and it draws the smoke through the water.