This review discusses the methods for recovering chitin from marine organisms, comparing enzymatic and chemical treatments for deproteinization and demineralization. It also covers the conditions for chitosan preparation, which significantly affect its degree of acetylation and molecular weight. Characterization techniques for chitin and chitosan are outlined, highlighting the role of their solubility in relation to their chemical structure. Biological activities of chitin and chitosan, including antibacterial, antifungal, antitumor, and antioxidant properties, are presented. The relationship between chemical structure and biological activity is demonstrated for chitosan with varying degrees of acetylation and molecular weight. Selected pharmaceutical and biomedical applications of chitin and chitosan are discussed, emphasizing their biocompatibility and biodegradability. Chitin is a natural polysaccharide found in the exoskeletons of arthropods and in the cell walls of fungi and yeast. It is primarily sourced from crab and shrimp shells. Chitin is extracted through acid treatment to dissolve calcium carbonate and alkaline treatment to dissolve proteins. Additional steps may be used to remove pigments. Chitin can be transformed into chitosan through partial deacetylation. Chitin and chitosan have various applications, including drug delivery, wound dressing, and biofilms. Chitin is a natural, biocompatible, and biodegradable polymer, making it suitable for biomedical and pharmaceutical applications. Chitin can exist in two allomorphs, α and β, which differ in their crystalline structures and solubility properties. α-chitin is the most abundant form, found in fungal cell walls and crustacean tissues. β-chitin is less common and found in association with proteins in squid pens and certain worms. Chitin extraction involves deproteinization and demineralization, which can be achieved through chemical or enzymatic methods. Chemical methods are often used, but enzymatic methods are gaining attention due to their ability to preserve the structure of chitin. Fermentation using microorganisms is also employed for chitin extraction, offering advantages such as reduced environmental impact and higher purity. Chitosan is a random copolymer derived from chitin through deacetylation. Its properties, including solubility, degree of acetylation, and molecular weight, are crucial for its applications. Chitosan is characterized using techniques such as NMR and viscometry. Its solubility in acidic solutions is influenced by its degree of acetylation. Chitosan has various biological activities, including antimicrobial and antifungal properties, and is used in biomedical applications due to its biocompatibility and biodegradability. The preparation and characterization of chitosan involve deacetylation, which can be achieved through chemical or enzymatic methods. Enzymatic deacetylation is preferred for its controlled and non-degradable process. Chitosan-based materials are processed into various formsThis review discusses the methods for recovering chitin from marine organisms, comparing enzymatic and chemical treatments for deproteinization and demineralization. It also covers the conditions for chitosan preparation, which significantly affect its degree of acetylation and molecular weight. Characterization techniques for chitin and chitosan are outlined, highlighting the role of their solubility in relation to their chemical structure. Biological activities of chitin and chitosan, including antibacterial, antifungal, antitumor, and antioxidant properties, are presented. The relationship between chemical structure and biological activity is demonstrated for chitosan with varying degrees of acetylation and molecular weight. Selected pharmaceutical and biomedical applications of chitin and chitosan are discussed, emphasizing their biocompatibility and biodegradability. Chitin is a natural polysaccharide found in the exoskeletons of arthropods and in the cell walls of fungi and yeast. It is primarily sourced from crab and shrimp shells. Chitin is extracted through acid treatment to dissolve calcium carbonate and alkaline treatment to dissolve proteins. Additional steps may be used to remove pigments. Chitin can be transformed into chitosan through partial deacetylation. Chitin and chitosan have various applications, including drug delivery, wound dressing, and biofilms. Chitin is a natural, biocompatible, and biodegradable polymer, making it suitable for biomedical and pharmaceutical applications. Chitin can exist in two allomorphs, α and β, which differ in their crystalline structures and solubility properties. α-chitin is the most abundant form, found in fungal cell walls and crustacean tissues. β-chitin is less common and found in association with proteins in squid pens and certain worms. Chitin extraction involves deproteinization and demineralization, which can be achieved through chemical or enzymatic methods. Chemical methods are often used, but enzymatic methods are gaining attention due to their ability to preserve the structure of chitin. Fermentation using microorganisms is also employed for chitin extraction, offering advantages such as reduced environmental impact and higher purity. Chitosan is a random copolymer derived from chitin through deacetylation. Its properties, including solubility, degree of acetylation, and molecular weight, are crucial for its applications. Chitosan is characterized using techniques such as NMR and viscometry. Its solubility in acidic solutions is influenced by its degree of acetylation. Chitosan has various biological activities, including antimicrobial and antifungal properties, and is used in biomedical applications due to its biocompatibility and biodegradability. The preparation and characterization of chitosan involve deacetylation, which can be achieved through chemical or enzymatic methods. Enzymatic deacetylation is preferred for its controlled and non-degradable process. Chitosan-based materials are processed into various forms