A candle flame has three main zones, which are given below:

Zone 3 (Non-Luminous Zone): It is the outermost zone. It is almost invisible and the hottest part of the flame. With sufficient oxygen, Complete combustion occurs here.

Zone 2 (Luminous Zone): It is the middle zone, which is typically yellow and bright. Incomplete combustion occurs here.

Zone 1 (Dark Inner Zone): It is the innermost zone closest to the wick. It is the coolest part of the flame, where combustion doesn't occur. It also contains unburnt fuel vapor.