This document defines and compares different types of parallelograms: rectangles, rhombi, squares. It states that a square is a special type of rectangle and rhombus, having all sides of equal length and all interior angles of 90 degrees. While all squares are rectangles and rhombi, not all rectangles or rhombi are squares. It also provides properties of rhombi, including that their diagonals are perpendicular and bisect the interior angles.