So I know that complete combustioncomplete combustion is a process where a fuel +reacts with $\ce{O2}$ which becomesto become $\ce{CO2 + H2O}$$\ce{CO2}$ and $\ce{H2O}$. But what is incomplete combustionincomplete combustion?
According to the Internet, $\ce{CH4 + O2}$ and $\ce{C6H12O6 + O2}$ are examples of incomplete combustion. I don't know why, please help me understand …What makes them so?