 The properties of a square are all of the same properties as a parallelogram, a rectangle, and a rhombus. So if we list out all of those properties, they're properties that you should already know. So the properties of a parallelogram, opposite sides are parallel, opposite sides are congruent, opposite angles are congruent, diagonals bisect each other, consecutive angles are supplementary. From a rectangle we know that the four angles have to be right angles, the diagonals are congruent, and from a rhombus we know that the four sides are congruent, the diagonals are perpendicular, and lastly the diagonals bisect the opposite angles. So all of the properties of a parallelogram, a rectangle, and a rhombus would be the properties of a square.