Bio-plastics – or bio-based polymers – are not one single substance. The term refers to a whole family of materials. Generally speaking, a bio-plastic is either bio-based or biodegradable. Bio-based materials are (at least partly) derived from plants/animals (biomass) and are often fully compostable but may require higher levels of heat, water, oxygen and micro-organisms to fully break down than what a home compost can provide – so are suitable for industrial composting only. The term bio can be misleading, as it suggests that it is definitely envionmentally-friendly. Biodegradation does not depend on the resource basis of a material but instead is linked to its chemical structure. Bio-based plastics should not be automatically assumed to mean the product will compost or even biodegrade. In other words, 100 per cent bio-based plastics may be non-biodegradable and noncompostable, and 100 per cent fossil-based plastics can be biodegradable and even compostable. Bio-plastics can include fossil-based plastics, if they are biodegradable. Therefore, a bio-plastic could be 100% biodegradable and 100% compostable and yet not be considered sustainable.