Fire is not a living thing. Fire is a process: it is the fast combustion of a material. The flame, which is yellow-orange part we usually see, is actually a mixture of gases that are reacting with one another. Depending on the type of gas, you can get different flame colors.

Fire is not a living creature in the way we usually talk about life. However, there are many chemical reactions that take place to keep the fire going (or keep it "alive," if you'd like).

Normally, fire is not considered to be life because it contains no knowledge that is passed on as fire spreads. It's just a chemical reaction that can sustain itself and spread. Living things pass on their DNA and the knowledge that DNA contains, which is what makes them different from fire.