Till date, market is augmented with a huge number of improved drug delivery systems. The success in this area is basically due to biodegradable polymers. Although conventional systems of drug delivery utilizing the natural and semisynthetic polymers so long but synthetic polymer gains success in the controlled drug delivery area due to better degradation profile and controlled network and functionality. The polyesters are the most studied class group due the susceptible ester linkage in their backbone. The Poly(glycolic Acid) (PGA), Poly(lactic acid) (PLA), and Polylactide-co-glycolide (PLGA) are the best profiled polyesters and are most widely used in marketed products. These polymers, however, still are having drawbacks which failed them to be used in platform technologies like matrix systems, microspheres, and nanospheres in some cases. The common problems arose with these polymers are entrapment inefficiency, inability to degrade and release drugs with required profile, and drug instability in the microenvironment of the polymers. These problems are forcing us to develop new polymers with improved physicochemical properties. The present review gave us an insight in the various structural elements of Poly(glycolic acid), polyester, with in depth study. The first part of the review focuses on the result of studies related to synthetic methodologies and catalysts being utilized to synthesize the polyesters. However the author will also focus on the effect of processing methodologies but due some constraints those are not included in the preview of this part of review. 1. Introduction Biodegradablepolymers can be efficiently utilized for various purposes such as drug delivery, orthopaedic, dental, and tissue engineering [1–7]. Such sophisticated applications usually require polymers with narrowly defined material properties. For a polymer to be used in drug delivery system, it is desired that it should degrade in prerequisite manner [8–12]. The rate of degradation (Hydrolytic and proteolytic degradation) of any polymer chiefly depends on its primary structure properties (Backbone and functionality characteristics), and secondary structural properties such as morphology, mechanical properties (tensile strength and modulus), the thermal properties (glass transition temperature , softening or melting point, degradation temperature) and the viscoelastic properties (storage and Loss moduli and tan？δ). The quality of these physicochemical properties depends on the structural features, such as backbone characteristics, functionalities, and crystal packing
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