A few examples of objects that are parallelograms are street and traffic signs, the structures on the neck of a guitar and the United States Postal Service symbol found on its trucks, packages and other trademarked material. A parallelogram is a quadrilateral with both pairs of opposite sides being parallel.

Several shapes qualify as being parallelograms, including squares, rectangles and rhombuses. There are several pieces of criteria that a shape can meet to be a parallelogram. The first is that both pairs of opposite sides are parallel. The second is that both pairs of opposite sides are congruent. If they are congruent, they are also parallel. The third criteria is that one pair of opposite sides are congruent and parallel. If this is the case, then the other pair is also parallel. A shape does not need to fit all three criteria to be a parallelogram. But one definition must be met. The area of a parallelogram is found by multiplying a base by its corresponding altitude. The perimeter is the distance around the parallelogram or the sum of all its sides. The opposite angles of a parallelogram are equal. Consecutive angles of a parallelogram are supplementary, meaning their sum is equal to 180 degrees.