I-beams, also known as steel beams, are long strips of steel with an I-shaped cross-section. I-beams are divided into ordinary I-beams and light I-beams. They are sections of steel with an I-beam shape.

I-beams are mainly divided into common I-beams, light I-beams and wide flange I-beams. These are divided into wide, medium and narrow flange I-beams according to the flange to web height ratio. The first two are produced in sizes 10-60, i.e. with a corresponding height of 10 cm-60 cm. At the same height, light I-beams have narrow flanges, thin webs and light weights. The wide flange I-beam, also known as H-beam, has a section characterised by two parallel legs and no slope on the inside of the legs. It is an economic section steel and is rolled on a four-roller universal mill, so it is also known as a "universal I-beam". National standards have been formed for ordinary and light I-beams.