In geometry, a square is a regular quadrilateral. This means that it has four equal sides and four equal angles (90-degree angles, or right angles). It can also be defined as a rectangle in which two adjacent sides have equal length. A square with vertices ABCD would be denoted ABCD.
The square is the n=2 case of the families of n-hypercubes and n-orthoplexes.
The term hard landscape is used by practitioners of landscape architecture and garden design to describe the construction materials which are used to improve a landscape by design. The corresponding term soft landscape materials is used to describe plant materials. A wide range of hard landscape materials can be used, such as brick, gravel, rock or stone, concrete, timber, bitumen, glass, metals, etc. 'Hard landscape' can also describe outdoor furniture and other landscape products.