Polylactic acid or polylactic acid (PLA) is a polymer or bioplastic made up of elements similar to lactic acid, with properties similar to those of polyethylene terephthalate (PET) used to make packaging, but which can also be biodegradable under certain conditions at temperatures around 60 °C. It can degrade into water and carbon oxide. PLAs are produced by lactide ring-opening polymerization.[1]​.

It is a thermoplastic whose base materials are obtained from corn or cassava starch, or sugar cane.

This plastic material is being widely used in sectors such as food, packaging or others, through injection molds, to obtain thousands or millions of identical pieces that allow these pieces to be obtained at very reasonable costs in all aspects, but the main one, the environmental one, because it is biodegradable after use.

Injection molds concentrate a large optimal production capacity for high needs for identical parts, being a much more recommended technology than 3D printing because the final costs are lower.

It is used in 3D printing in the process called fused deposition modeling (FDM).

The name "polylactic acid" does not meet the criteria for the IUPAC standard nomenclature, and is therefore potentially ambiguous and confusing, since PLA is not a polyacid (polyelectrolyte), but rather a polyester.[1]​.