Square - perimeter and area

A square is a four-sided polygon, or quadrilateral, in which all four sides have exactly the same length and all four interior angles are right angles of 90 degrees. It is the most symmetric of all quadrilaterals and can be seen as a special case of both the rectangle and the rhombus, combining equal sides with equal angles. Its two diagonals are equal in length, cross at the centre, and bisect each other at right angles, splitting the square into congruent triangles. Because every square is fully described by a single number, its side length, both its area and its perimeter are easy to determine once that one measurement is known. The area tells you how much surface the square covers, while the perimeter measures the total distance around its edge. This clean, predictable structure makes the square one of the first shapes children learn and a cornerstone of plane geometry. In everyday life it appears everywhere, from floor and wall tiles to chessboards, photo frames, and the pixels and grid cells that structure digital screens. Architects, engineers, and designers rely on it constantly, since square modules are simple to measure, repeat, and fit together without wasted space.