The review discusses the functional and bioactive properties of collagen and gelatin from alternative sources, emphasizing their increasing importance in food, pharmaceutical, and cosmetic applications. Collagen and gelatin are derived from various sources, including mammalian and non-mammalian species, with traditional sources being pig skin, bovine hide, and pork/cattle bones. However, there is growing interest in using collagen and gelatin from fish, poultry, and other non-mammalian sources due to their potential for novel applications and sustainability. The properties of collagen and gelatin are influenced by their source, age of the animal, and type of collagen. Gelatin is primarily used for its gel-forming and viscoelastic properties, but recent studies have explored its use in emulsifiers, foaming agents, stabilizers, and biodegradable films. Enzymatic hydrolysis of collagen and gelatin has led to the production of bioactive peptides with antimicrobial, antioxidant, and antihypertensive properties. The functional properties of gelatin are influenced by its molecular weight, amino acid composition, and processing conditions. Alternative sources of collagen and gelatin, such as fish, poultry, and marine species, have been studied for their potential in food and biomedical applications. The review also highlights the importance of differentiating gelatins from various sources for safety and religious reasons, as well as the development of methods for species identification. The functional properties of collagen and gelatin include gelling, water binding, surface properties, film-forming capabilities, and microencapsulation. These properties are influenced by factors such as molecular weight, amino acid composition, and processing conditions. The review concludes that collagen and gelatin from alternative sources have significant potential for various applications, including food, pharmaceutical, and biomedical uses, and that further research is needed to optimize their extraction and processing for improved functionality and sustainability.The review discusses the functional and bioactive properties of collagen and gelatin from alternative sources, emphasizing their increasing importance in food, pharmaceutical, and cosmetic applications. Collagen and gelatin are derived from various sources, including mammalian and non-mammalian species, with traditional sources being pig skin, bovine hide, and pork/cattle bones. However, there is growing interest in using collagen and gelatin from fish, poultry, and other non-mammalian sources due to their potential for novel applications and sustainability. The properties of collagen and gelatin are influenced by their source, age of the animal, and type of collagen. Gelatin is primarily used for its gel-forming and viscoelastic properties, but recent studies have explored its use in emulsifiers, foaming agents, stabilizers, and biodegradable films. Enzymatic hydrolysis of collagen and gelatin has led to the production of bioactive peptides with antimicrobial, antioxidant, and antihypertensive properties. The functional properties of gelatin are influenced by its molecular weight, amino acid composition, and processing conditions. Alternative sources of collagen and gelatin, such as fish, poultry, and marine species, have been studied for their potential in food and biomedical applications. The review also highlights the importance of differentiating gelatins from various sources for safety and religious reasons, as well as the development of methods for species identification. The functional properties of collagen and gelatin include gelling, water binding, surface properties, film-forming capabilities, and microencapsulation. These properties are influenced by factors such as molecular weight, amino acid composition, and processing conditions. The review concludes that collagen and gelatin from alternative sources have significant potential for various applications, including food, pharmaceutical, and biomedical uses, and that further research is needed to optimize their extraction and processing for improved functionality and sustainability.