The branch of mathematics that deals with the study of shapes and sizes is called geometry. Geometry explores properties and relationships of points, lines, surfaces, and solids in space. It encompasses various subfields, including Euclidean geometry, which focuses on flat surfaces, and non-Euclidean geometries, which study curved spaces. Geometry has practical applications in fields such as architecture, engineering, and computer graphics, making it foundational to both theoretical and applied mathematics. The study of geometric figures, transformations, congruence, and symmetry is essential for understanding spatial relationships and structures.