Chitosan is a natural, biodegradable polymer derived from chitin, which is mainly obtained from the shells of crustaceans such as shrimp, crab, and lobster. Due to its unique properties like biocompatibility, non-toxicity, biodegradability, and mucoadhesive nature, chitosan has gained significant attention in pharmaceutical and biomedical fields. This review focuses on the source, preparation, chemical structure, and various properties of chitosan, including physical, chemical, and biological characteristics. It also highlights the advantages and limitations associated with its use. Furthermore, the review discusses the wide range of applications of chitosan in drug delivery systems, wound healing, tissue engineering, food preservation, and water treatment. Special emphasis is given to its role in controlled and sustained drug delivery, where it works through mechanisms such as swelling, gel formation, diffusion, erosion, and permeation enhancement. Overall, chitosan is considered a promising natural polymer with extensive potential in modern drug delivery and biomedical applications, although certain limitations like pH-dependent solubility and variability need to be addressed
*Mr. Prashant Sunil Dhokare, Miss. Rutuja Shah, Mr. Akshy Mane, Mr. Sangram Bhogam, Mr. Ritesh Bhosle (Fri,) studied this question.