What is combustion in chemistry for types of reactions ?

Combustion is a type of reaction in which the products yield CO2 (Carbon Dioxide) and H2O (Water).

In order for a reaction to be combustion, it must yield the above products with any amount of moles; the subscripts cannot change as that would then change the actual compound.

Combustion reactions typically have Hydrocarbon's in the reactants.

Hope this helps!