This document defines and compares properties of rhombuses, rectangles, and squares. A rhombus is a parallelogram with 4 congruent sides and perpendicular diagonals. A rectangle is a parallelogram with 4 right angles and congruent diagonals. A square has the combined properties of a rhombus, rectangle, and parallelogram - it is a rhombus and rectangle with 4 equal sides and right angles.