Chitosan, a natural polycationic polysaccharide derived from chitin, has gained attention for its biomedical and pharmaceutical applications. Despite its low solubility in neutral and alkaline solutions, chemical modifications into composites or hydrogels enhance its functional properties. Chitosan is recognized as a versatile biomaterial due to its non-toxicity, low allergenicity, biocompatibility, and biodegradability. Recent research highlights its potential in various applications, including pharmaceuticals, biomedical uses, and environmental remediation. Chitosan is produced from chitin, primarily from crustacean shells, through chemical or enzymatic deacetylation. Its properties, such as degree of deacetylation and molecular weight, influence its solubility and functionality. Chitosan hydrogels, composites, and derivatives have been developed for applications in tissue engineering, drug delivery, wound healing, and water treatment. Chitosan exhibits antibacterial and antifungal activities, with its effectiveness influenced by molecular weight, degree of acetylation, and environmental pH. It has shown potent antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as fungi. Chitosan derivatives have also demonstrated antitumor activity by inducing apoptosis in cancer cells and inhibiting tumor growth. Chitosan's antioxidant properties are attributed to its ability to scavenge free radicals, making it useful in combating oxidative stress. Its applications in drug delivery include controlled release systems, targeted drug delivery, and mucoadhesive formulations. Chitosan-based hydrogels and nanofibers have been utilized in wound healing due to their biocompatibility, antimicrobial properties, and ability to promote tissue regeneration. In water treatment, chitosan is effective in adsorbing pollutants such as dyes, metals, and organic compounds. Modifications like cross-linking and grafting enhance its adsorption capacity and specificity. Chitosan-based materials have also been employed in environmental remediation, such as the removal of heavy metals and toxic substances. Overall, chitosan and its derivatives offer a wide range of applications in biomedical and pharmaceutical fields, as well as environmental applications, due to their unique properties and biocompatibility. Continued research and development are expected to expand its potential uses in various industries.Chitosan, a natural polycationic polysaccharide derived from chitin, has gained attention for its biomedical and pharmaceutical applications. Despite its low solubility in neutral and alkaline solutions, chemical modifications into composites or hydrogels enhance its functional properties. Chitosan is recognized as a versatile biomaterial due to its non-toxicity, low allergenicity, biocompatibility, and biodegradability. Recent research highlights its potential in various applications, including pharmaceuticals, biomedical uses, and environmental remediation. Chitosan is produced from chitin, primarily from crustacean shells, through chemical or enzymatic deacetylation. Its properties, such as degree of deacetylation and molecular weight, influence its solubility and functionality. Chitosan hydrogels, composites, and derivatives have been developed for applications in tissue engineering, drug delivery, wound healing, and water treatment. Chitosan exhibits antibacterial and antifungal activities, with its effectiveness influenced by molecular weight, degree of acetylation, and environmental pH. It has shown potent antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as fungi. Chitosan derivatives have also demonstrated antitumor activity by inducing apoptosis in cancer cells and inhibiting tumor growth. Chitosan's antioxidant properties are attributed to its ability to scavenge free radicals, making it useful in combating oxidative stress. Its applications in drug delivery include controlled release systems, targeted drug delivery, and mucoadhesive formulations. Chitosan-based hydrogels and nanofibers have been utilized in wound healing due to their biocompatibility, antimicrobial properties, and ability to promote tissue regeneration. In water treatment, chitosan is effective in adsorbing pollutants such as dyes, metals, and organic compounds. Modifications like cross-linking and grafting enhance its adsorption capacity and specificity. Chitosan-based materials have also been employed in environmental remediation, such as the removal of heavy metals and toxic substances. Overall, chitosan and its derivatives offer a wide range of applications in biomedical and pharmaceutical fields, as well as environmental applications, due to their unique properties and biocompatibility. Continued research and development are expected to expand its potential uses in various industries.