Structural biology is the branch of molecular biology that focuses on understanding the three-dimensional structures of biological macromolecules such as proteins, nucleic acids, and complexes. The structure of these molecules is closely related to their function, and studying their architecture helps explain how they perform their roles in the cell. Structural biology uses techniques like X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, cryo-electron microscopy (cryo-EM), and molecular modeling to visualize and analyze biomolecular structures at atomic resolution. This knowledge is essential for understanding enzyme mechanisms, molecular recognition, and signal transduction. Structural biology also plays a critical role in drug design by revealing binding sites and interaction patterns. Insights gained from this field contribute significantly to advances in medicine, biotechnology, and our overall understanding of cellular function and disease.