Structural steel is a category of steel used for making construction materials in a variety of shapes. Many structural steel shapes take the form of an elongated beam having a profile of a specific cross section. Structural steel shapes, sizes, chemical composition, mechanical properties such as strengths, storage practices, etc., are regulated by standards in most industrialized countries. Most structural steel shapes, such as I-beams, have high second moments of area, which means they are very stiff in respect to their cross-sectional area and thus can support a high load without excessive sagging.

The shapes available are described in many published standards worldwide, and a number of specialist and proprietary cross sections are also available.

The shapes available are described in many published standards worldwide, and a number of specialist and proprietary cross sections are also available.

• I-beam (I-shaped cross-section – in Britain these include Universal Beams (UB) and Universal Columns (UC); in Europe it includes the IPE, HE, HL, HD and other sections; in the US it includes Wide Flange (WF or W-Shape) and H sections)
• MS Angle (L-shaped cross-section)
• MS Channel, or C-beam, or C cross-section
• Tee (T-shaped cross-section)
• MS Flats – Bar a long piece with a rectangular cross section, but not so wide so as to be called a sheet.
• Rod, a round or square section long compared to its width; see also rebar and dowel.
• Open web steel joist

While many sections are made by hot or cold rolling, others are made by welding together flat or bent plates.