A parallelogram is a two-dimensional geometrical shape with four sides, where the opposite sides are parallel and equal in length. The angles inside two sides must add up to 180°, and the opposite angles are equal. A parallelogram is a special type of quadrilateral that has both pairs of opposite sides parallel and equal. The congruence of opposite sides and opposite angles is a direct consequence of the Euclidean parallel postulate. The perimeter of a parallelogram is the sum of the length of all its sides, which is 2 times the (base + side length). The area of a parallelogram is given by the formula A = bh, where b is the length of the base, and “h” is the height. A parallelogram can be classified into three main types: square, rectangle, and rhombus.