system
Given the following post, respond as if you're commenting on Reddit:
human
Why does a puff of smoke appear when a candle goes out?
gpt
Incomplete combustion. A lit candle flame is in a constant mix of gas that is combusting and giving off light. 

When you blow it out, you remove one of the the three things you need for fire - heat. By blowing cooler air in the flame, the gases rapidly lose heat, combustion stops, and the reaction stops emitting light. The cooling gas also condenses, forming the small cloud or puff. 

The smoke that comes from the wick is the same thing, wax from the wick is evaporating under the retained heat of the wick but rapidly cools in air, condensing and forming a little cloud you can see.