Fibronectins are large glycoproteins involved in a wide range of cellular functions, including cell adhesion, morphology, cytoskeletal organization, migration, differentiation, oncogenic transformation, phagocytosis, and hemostasis. They are synthesized by various cells and found in body fluids, connective tissues, and basement membranes. Fibronectins have a complex molecular structure with multiple specific binding sites, and their functions can be understood in terms of this structure. The article reviews the current understanding of fibronectin structure and properties, focusing on overall concepts, recent developments, and future research directions. Fibronectins interact with various macromolecules, such as gelatin, collagens, fibrin, heparin, and proteoglycans. They are also involved in cell adhesion to solid substrates, cell spreading, and the formation of microfilament bundles. Fibronectins play a role in phagocytosis, hemostasis, thrombosis, and cell migration. The carbohydrate content of fibronectin is important for stability but not for biological activities. Cellular and plasma fibronectins are structurally and functionally similar but not identical, with differences in pl, solubility, and subunit linkage. The modular structure of fibronectin allows for the development of antibodies specific for different functional regions, aiding in further research. The complex interactions of fibronectin with other molecules and its involvement in various biological phenomena require further investigation.Fibronectins are large glycoproteins involved in a wide range of cellular functions, including cell adhesion, morphology, cytoskeletal organization, migration, differentiation, oncogenic transformation, phagocytosis, and hemostasis. They are synthesized by various cells and found in body fluids, connective tissues, and basement membranes. Fibronectins have a complex molecular structure with multiple specific binding sites, and their functions can be understood in terms of this structure. The article reviews the current understanding of fibronectin structure and properties, focusing on overall concepts, recent developments, and future research directions. Fibronectins interact with various macromolecules, such as gelatin, collagens, fibrin, heparin, and proteoglycans. They are also involved in cell adhesion to solid substrates, cell spreading, and the formation of microfilament bundles. Fibronectins play a role in phagocytosis, hemostasis, thrombosis, and cell migration. The carbohydrate content of fibronectin is important for stability but not for biological activities. Cellular and plasma fibronectins are structurally and functionally similar but not identical, with differences in pl, solubility, and subunit linkage. The modular structure of fibronectin allows for the development of antibodies specific for different functional regions, aiding in further research. The complex interactions of fibronectin with other molecules and its involvement in various biological phenomena require further investigation.