​Different types of quadrangles and their definitions, properties and graphics are introduced. A parallelogram is called a parallelogram when two opposite sides are parallel. A parallelogram with four angles at right angles is called a rectangle. A quadrilateral with four equal sides is called a diamond. A quadrilateral with four equal sides, four equal angles and all right angles is called a square. At least one set of parallelograms on opposite sides is called trapezoids. The quadrilateral with two adjacent sides equal each other is called zither shape.