Slabs are structural members that support transverse loads and transfer them to supports via bending. They are commonly used as floors and roofs. One-way slabs bend in only one direction across the shorter span like a wide beam, while two-way slabs bend in both directions if the ratio of longer to shorter span is less than or equal to 2. Design of one-way slabs involves calculating bending moment and shear force, selecting reinforcement ratio and bar size, and checking deflection, shear, and development length.