Cellular respiration is one of the most important processes for life. It is part of the metabolism process that takes place for most living things, including humans.
The idea is that this is the way the cells turn fuel, often sugars in the form of glucose, and use the reductive properties of oxygen to produce ATP (adenosine triphosphate). This ATP is one of the most fundamental units of energy in the living world.
The chemical reaction that happens in this process is this:
C6H12O6 (s) + 6 O2 (g) → 6 CO2 (g) + 6 H2O (l) + heat + ATP
There is a series of steps that happens, and the most high-energy steps are the ones that have oxygen in them. This is why living things need to breathe oxygen to survive! Cellular respiration starts off with the process of glycolysis, which produces the pyruvate (one of the chemicals) necessary for the rest of the energy production.
It produces just a bit of energy itself, but the most important fact is that it kicks of the next step. That is the Krebs Cycle, or the Citric Acid Cycle. This is named for the scientist who discovered it or the substances that are a part of it (the citric acid).
In the end, the products are important because they generate substances that have a high level of energy in their bonds. The ATP is the way this energy is stored, and the body can use it whenever it needs energy!
It takes some energy investment to get the ATP from the starting glucose molecule, usually 2 ATP. The products of the cellular respiration process is anywhere from 30-32 ATP, depending on the way that the products of the citric acid cycle are oxidized.
Therefore, it is an important process because it produces over 15x what it costs to do! That is, as long as you have enough oxygen and glucose to power the process.
