Arginyl-glycyl-aspartic acid (RGD) is a tripeptide composed of L-arginine, glycine, and L-aspartic acid. It is a well-defined and highly conserved cell adhesion sequence found in numerous extracellular matrix proteins, such as fibronectin, vitronectin, and fibrinogen. The RGD motif serves as the primary recognition site for a family of cell surface receptors known as integrins, including αvβ3, αvβ5, and α5β1. The primary application of RGD peptides is in biomedical research and drug development. They are extensively used as tools to study cell adhesion, migration, signaling, and angiogenesis. Synthetic RGD peptides and their cyclic analogs can act as competitive inhibitors of integrin-ligand interactions, making them valuable for investigating cancer metastasis, thrombosis, and inflammatory diseases. Furthermore, RGD sequences are incorporated into biomaterials, drug delivery systems, and tissue engineering scaffolds to promote specific cell attachment and enhance biocompatibility. Due to its critical role in mediating cell-matrix interactions, the RGD peptide is a fundamental building block in the design of novel therapeutic agents, diagnostic probes, and advanced biomaterials targeting integrin-related pathways.