What are parallegrams?
A parallelogram is a 4 sided figure where the opposite sides are parallel. Ok...that still might not have helped much. What it means to say, "the opposite sides are parallel" is that if you were to keep extending them out both directions, they would never touch.
Squares and rectangles are parallelograms. As is the rhombus.
Matt
For more information:
http://en.wikipedia.org/wiki/Parallelogram