The term biodegradable plastic refers to polymers that can decompose under the action of micro-organisms (bacteria, fungi), forming water, carbon dioxide (or methane) and biomass that is not dangerous for the environment.
Biodegradation can take place in different environments (compost, soil, water, etc.) and will be more or less rapid depending on different parameters such as temperature, humidity, presence of micro-organisms and of course the nature of the polymer itself.
The biodegradable character of a polymer is not linked to the resource with which it was produced but only to its chemical structure. Thus, there are biodegradable plastics made from both fossil and renewable resources.