Diffraction is the bending of light waves around an object in it's path. This is due to light's being a wave, and how it spreads out from the source, not in straight lines, but in curved waves. This is perhaps best shown in something we see every day, your very own shadow. Shadows are not sharp images, they are fuzzy around the edges, this is due to diffraction. As light rays hit you, the waves bend around you and then continue on, but they have been changed, and so the image projected on the ground is no longer sharp. If light was a beam, it would hit you straight on, and you would get a sharp image on the ground, thus supporting the wave theory on light. This is also the reason why things far away appear blurred or fuzzy, because the light has bent as it moved around the object. This effect is multiplied at large distances, making it necessary for corrections to be made in devices' lenses (i.e. telescopes and binoculars). Diffraction is usually done using a single or double slit filter, or through something called a diffraction grating. The double slit filters the light more than the single, and providing very clear order lines, as well as more of them to be observed. When viewed through a single slit, double slit, or diffraction grating, the light is filtered into bright and dark bands. There is always a very pronounced, and brighter band directly in the middle, which is called the central bright band. From there, the pairs, or order lines are numbered, the first pair are called the first order lines, the second the second order lines, and so on.