What Are Squares?

Squares have four perpendicular sides of equal length

Squares have four sides, all the same length. Both sets of parallel and equal sides are perpendicular to each other. This also means that all four angles in a square are right ($90^\circ$) angles.

In fancier terms, squares are regular quadrilateral polygons: all their sides have the same length, and all their angles have the same measure.

Each of the blue shapes below is a square. The red shape is not (but it is a rectangle.

Area:

You can find the area of a square by squaring the length of one of the sides: $\text{side}^2$.

Relationship to other quadrilaterals:

Squares are parallelograms with sides that are equal length and perpendicular.

Squares are rectangles with equal length sides.

Squares are rhombi with perpendicular sides.

Squares are kites where the opposite sides are parallel and all the angles between adjacent sides are right angles.