A square is a two-dimensional closed figure with four equal sides and four right angles. In other words, a square is a rectangle with all four sides of equal length. The following figure is a square.
Opposite sides are parallel
All sides are equal
Each of the interior angle is equal to 90 degrees
The sum of all interior angles is 360 degrees.
The four right angles are shown with the special red symbol and one green marking on each side shows that all 4 sides are equal.