Biodegradability is the ability of a material to be biodegraded. It is a natural process in which a material, through biological action, changes and generally loses its original properties and at a chemical level the molecules that make it up become simpler and more stable forms.

It can be the most oxidized form of the original molecule (for carbon materials the most oxidized form is carbon dioxide CO), the most reduced form (for carbon it is methane CH) or a mixture of both.

Any organic material can be degraded by biological means, such as plants, animals, microorganisms and fungi, under natural environmental conditions.[1]​ During the biodegradation process, the material will be used by biological agents as a substrate, that is, a source of carbon and other nutrients essential for health.

In general, all organic substances and materials are biodegradable; The degradation time will depend on various factors such as: the complexity of the substance, the availability and types of degrading organisms, whether the material is bioavailable, the environment in which it is found, etc. Substances that tend to remain in the environment for a longer time are known as recalcitrant.

Biodegradation[2]​ is the characteristic of some chemical substances that they can be used as a substrate by microorganisms, which use them to produce energy in general through two metabolic pathways: aerobic respiration in which the final electron donor is oxygen and anaerobic respiration in which the final electron donor can be sulfur, phosphorus or another element.

It can be used to eliminate certain contaminants such as some municipal solid waste, food waste, garden waste, paper, cardboard, etc.

Biodegradation is widely used for the treatment of organic waste in compost plants, in wastewater treatment, and treatment of soils contaminated with pesticides, hydrocarbons or other substances. However, in discharges that contain biodegradable matter, these treatments may not be effective if we find other substances such as heavy metals, or if the medium has an extreme pH. In these cases, prior treatment is necessary to leave the spill in conditions in which the bacteria can perform their function at an acceptable speed.

Inorganic substances also suffer degradation processes in general due to physical or chemical processes such as erosion or oxidation, but there is no biological action in general.