The article reviews the functional and bioactive properties of collagen and gelatin derived from alternative sources, highlighting recent advancements in extraction methods, processing conditions, and novel applications. Gelatin, a by-product of collagen extraction, is widely used in food, photography, cosmetics, and pharmaceuticals due to its gel-forming properties. Recent studies have explored its use in emulsifiers, foaming agents, colloid stabilizers, biodegradable films, and micro-encapsulation. Enzymatic hydrolysis of collagen and gelatin has led to the production of bioactive peptides with antimicrobial, antioxidant, and antihypertensive properties, which have shown excellent absorption and metabolism in animal and human models. The article discusses the extraction of collagen and gelatin from various sources, including fish and poultry, and the challenges and opportunities in these alternative sources. Fish gelatin, in particular, has shown promising rheological properties and thermostability, though it is less versatile than mammalian gelatins. The functional properties of collagen and gelatin are categorized into gelling and water binding, surface, and film-forming properties. These properties are influenced by factors such as molecular weight, amino acid composition, and processing conditions. The article also covers methods for species differentiation of gelatins, which is important for safety and religious reasons, and the use of natural polyampholytic hydrogels and cross-linking agents to enhance the functional properties of gelatin. Finally, the article explores the potential of gelatin and collagen in microencapsulation, where they can encapsulate functional components to control release and protect against degradation. The use of natural cross-linkers and complex systems has been shown to improve the mechanical strength and thermal stability of microcapsules, making them suitable for various applications.The article reviews the functional and bioactive properties of collagen and gelatin derived from alternative sources, highlighting recent advancements in extraction methods, processing conditions, and novel applications. Gelatin, a by-product of collagen extraction, is widely used in food, photography, cosmetics, and pharmaceuticals due to its gel-forming properties. Recent studies have explored its use in emulsifiers, foaming agents, colloid stabilizers, biodegradable films, and micro-encapsulation. Enzymatic hydrolysis of collagen and gelatin has led to the production of bioactive peptides with antimicrobial, antioxidant, and antihypertensive properties, which have shown excellent absorption and metabolism in animal and human models. The article discusses the extraction of collagen and gelatin from various sources, including fish and poultry, and the challenges and opportunities in these alternative sources. Fish gelatin, in particular, has shown promising rheological properties and thermostability, though it is less versatile than mammalian gelatins. The functional properties of collagen and gelatin are categorized into gelling and water binding, surface, and film-forming properties. These properties are influenced by factors such as molecular weight, amino acid composition, and processing conditions. The article also covers methods for species differentiation of gelatins, which is important for safety and religious reasons, and the use of natural polyampholytic hydrogels and cross-linking agents to enhance the functional properties of gelatin. Finally, the article explores the potential of gelatin and collagen in microencapsulation, where they can encapsulate functional components to control release and protect against degradation. The use of natural cross-linkers and complex systems has been shown to improve the mechanical strength and thermal stability of microcapsules, making them suitable for various applications.