Waffle slabs are reinforced concrete slabs reinforced in two orthogonal directions, forming a ribbed plate. They are characterized by their total edge height, lightening block height, rib spacing, rib thickness, and compression layer thickness. Waffle slabs can adequately support distributed and point loads in two directions. Benefits include flexibility, light weight allowing longer spans, fast construction, slim depths, robustness, vibration control, thermal mass, and durability. Waffle slabs are constructed with ribs forming a grid pattern and solid fills at supports. Larger spans may use post-tensioning or joist construction. Proper design considers loads, materials, deformations, and tile installation compatibility.