PLA (Polylactic Acid) is a naturally biodegradable when exposed to the environment thermoplastic derived from renewable resources such as corn starch, potato, soy, tapioca or sugarcane and this fact makes PLA the most environmentally friendly solution in the domain of 3D printing. It is one of the most popular bioplastics, used for many applications ranging from plastic cups to medical implants.
For example, a PLA bottle left in the ocean would typically degrade in six to 24 months. Compared to conventional plastics which in the same environment usually takes several hundred to a thousand years to degrade this is truly phenomenal.
PLA is ideal for 3D prints where aesthetics are important. Due to its lower printing temperature is easier to print with and therefore better suited for parts with fine details. PLA is generally considered as an odorless filament and might smell sweet as a candy.