Geometric solids are three-dimensional shapes that have length, width, and height. They can be classified into two main categories: polyhedra and non-polyhedra. Polyhedra, like cubes and pyramids, are made up of flat polygonal faces, while non-polyhedra include shapes like spheres and cylinders that have curved surfaces. These solids can be further described by their properties, such as the number of faces, edges, and vertices. For example, a cube has six faces, twelve edges, and eight vertices. Understanding geometric solids is essential in fields like mathematics, architecture, and engineering.