system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why does candle wax burn through a wick but not on its own?
gpt
Fire needs 3 things: heat, fuel, and oxygen.

A flat surface of solid or liquid wax doesn't have much surface area to interact with oxygen, and it has too much mass to be easily warmed up enough to evaporate the wax into a gas.

The wick solves both of these problems. A small amount of liquid wax is drawn up into the wick (like how water sucks up into a paper towel) and then evaporates in the heat of the flame. The gas-phase wax is able to mix with lots of oxygen in the air, completing the 3 requirements and easily burning. This creates heat, melting more wax, which gets drawn up into the wick...etc etc.