COMBUSTION
A combustion reaction takes place when a fuel and an oxidant react, producing heat or heat and light. The most recognizable form of combustion reaction is flame, with explosions being an even faster form of combustion reaction. A combustion can happen at a wide range of speeds, and can occur in many different environments, but the majority of combustions we know and recognize happen in a fairly limited spectrum.

DECOMPOSITION
A decomposition reaction is a type of chemical reaction in which a substance degrades into two or more basic components. It is a process in direct contrast to that of chemical synthesis, which involves molecular bonding so that two or more components may join to form a single chemical compound. The decomposition reaction often requires exposure to a catalyst, such as a heat source or solvent.

SYNTHESIS
A synthesis reaction or direct combination reaction is one of the most common types of chemical reactions. In a synthesis reaction two or more chemical species combine to form a more complex product.
A + B → AB

SINGLE-REPLACEMENT
A single replacement reaction, sometimes called a single displacement reaction, is a chemical reaction where one element replaces another element in a compound to increase stability. An example of a single replacement reaction that takes place in real life is when oxidation forms rust on cars.

DOUBLE-REPLACEMENT
double replacement reaction - a chemical reaction between two compounds where the positive ion of one compound is exchanged with the positive ion of another compound.