I-beams, also called universal beams, are structural steel profiles shaped like the capital letter “I”, with a central vertical web and horizontal flanges on the top and bottom. They are designed to bear high bending and shear loads while minimizing weight. I-beams are commonly used in construction, bridge building, shipbuilding, and heavy machinery manufacturing. The narrow flanges make them lighter than H-beams but still provide excellent strength for moderate spans and loads.