High-Density Polyethylene (HDPE) is not biodegradable. HDPE is a type of plastic that is known for its durability and resistance to degradation in natural environments. It is often used for items like plastic bottles, containers, and various other products because of its robust properties. However, these same properties that make HDPE plastic so useful also mean that it does not readily break down in the environment.

To clarify, biodegradable materials are substances that can be broken down by natural processes into non-toxic components, such as water, carbon dioxide, and biomass, with the help of microorganisms. HDPE does not meet this criteria, and it can persist in the environment for a very long time if not properly managed through recycling or disposal in a controlled manner.

If you're looking for more eco-friendly alternatives, you might want to consider materials like PLA (Polylactic Acid) or PHA (Polyhydroxyalkanoates), which are biodegradable plastics. However, it's important to note that even biodegradable plastics may not break down in all environments and may require specific conditions to degrade effectively.