A 3D shape is a solid figure or object that has three dimensions: length, width, and height. Unlike 2D shapes, 3D shapes have depth and occupy space, which is measured in terms of volume. Some examples of 3D shapes include cubes, rectangular prisms, spheres, cones, and cylinders. 3D shapes have faces, edges, and vertices, and they can be classified into several categories based on their shape and properties. For example, some 3D shapes have curved surfaces, while others are in the shape of pyramids or prisms. In mathematics, 3D shapes are studied in the concept of solids and can be applied in real life. Children learn about 3D shapes in school, starting from kindergarten where they learn to identify shapes as two-dimensional or three-dimensional, to first grade where they learn to compose two-dimensional and three-dimensional shapes.