Polylactic acid (PLA) is a biodegradable and biocompatible polymer that is widely used as a carrier in drug delivery systems and as a structural material for tissue engineering and medical implants. It acts as a controlled release matrix through ester bond hydrolysis, gradually releasing encapsulated drugs and metabolizing into non-toxic lactic acid. Polylactic acid possesses adjustable degradation rates, mechanical properties, and the ability to be combined with other polymers, making it suitable for localized or systemic drug delivery, orthopedic fixation devices, and 3D printed scaffolds for bone regeneration.