Poly(lactic acid) or polylactide (PLA) is the most extensively researched and utilized biodegradable and renewable thermoplastic polyester, with potential to replace conventional petrochemical-based polymers. In recent times, several PLA-based technologies have emerged with an emphasis on achieving chemical, mechanical, and biological properties equivalent or superior to conventional polymers. The frequent need for a chemical or physical modification of PLA to achieve suitable properties for its intended consumer and biomedical applications, however, has demanded significant attention in the last decade. In the first part of this review, we briefly discuss the advantages, limitations, production methods, and applications of unmodified PLA. The second part, the major objective of this paper, focuses on the various bulk and surface-modification strategies used to date and their basic principles, drawbacks, and achievements.