Concrete is "artificial stone" obtained by mixing cement, sand, and aggregates with water. Fresh concrete can be molded into almost any shape, which is an inherent advantage over other materials. Concrete became very popular after the invention of Portland cement in the 19th century; however, plain concrete does not easily withstand tensile and shear stresses caused by wind, earthquakes, vibrations, and other forces and is therefore unsuitable in most structural applications.

To overcome this weakness, steel rods are embedded in such a manner that the tensile strength of steel and the compressive strength of concrete work together in resisting forces. The reinforcing steel-rods, bars, or mesh absorbs the tensile shear, and sometimes the compressive stresses in a concrete structure..

Reinforced concrete developements in design and construction practice pioneered by European engineers in the late 19th century, revolutionized the construction industry and concrete became one of the world's most common building materials. At the present time, reinforced concrete is extensively used in a wide variety of engineering applications (e.g., buildings, bridges, dams).

“The city is not a concrete jungle, it is a human zoo. ” - Desmond Morris