Chitosan is a natural polysaccharide derived from chitin, the second most abundant biopolymer found in the exoskeletons of crustaceans, insects, and certain fungi. With remarkable biocompatibility, biodegradability, and non-toxic properties, chitosan is widely used in fields ranging from biomedicine to agriculture and water treatment. It exhibits excellent film-forming abilities, antimicrobial properties, and a unique capacity to bind with metals, making it a versatile material for applications like drug delivery, wound healing, and pollutant removal.