Paper is a three dimensionally manipulated five dimensional object designed to act as a canvas for two dimensional images. At first glance a primarily three dimensional being, such as Humans, may beleive that a "sheet" (essentically a pressed flat peice) is in fact two dimensional, simply because the dimensional footprint is not very large along the third dimension (or the second, or first, depending on orentation.)

This dimensional lacking has lead to several sayings. An example of this was given to me by a Physics teacher. His teacher told him once, regarding making a reference sheet for the complex formulas, "A sheet of paper has 6 sides- use them all."

Why lines like this are considered "witty" is yet unknown, but they certianly are considered "witty."

Paper is generally used with either a long, thin cylinder of graphte (commonly called "lead" for the same reason that trapizoidal prisims of frozen water are called "cubes") wrapped in a tube of wood and then sharpened to create a point at one end. Some that feel more daring (or are required too according to the rules) use a contraption that is essentially a long tube filled with ink connecting to a small ball in a cone. The ink is deposited on the ball, which rolls around in the cone until it contacts the paper. The ball then deposits the ink on the paper, and the ink then dries leaving a mark. These devices are commonly known as "pens."

Due to the flatness of paper, it can be folded into many interesting shapes. This practice is known as "paper airplanes" if the shape in that of a glider, "origami" if it's in the shape of a swan or other shape or "weaponry" if it's in the shape of a ball. Paper balls are also known as "garbage."