Before computer generated imaging (CGI), Japanese anime was made just like any other old cartoon, by hand drawing each frame. Anime is unique in its detail. If you watch American cartoons, you'll notice that the animation itself is more detailed - lots of movements with big blocks of color. For example, Home Simpson always wears a solid white shirt with solid blue pants, but there are more frames for his movements. Japanese anime, made for TV, shows a great deal of detail in the clothing, the shadows and backgrounds, but movement is more restricted. You'll often notice that the only thing moving is the mouth, but the head remains stationary. On the other hand, made for the wide screen, Japanese anime is incomparable in its detail and animation.

Anime cels, then, can be very beautiful. Look for these things when shopping for a cel:

• Line fading. The outlines are drawn on the outside of the cel, with the color blocked in on the back. Look for strong lines, but not thick ones. Thick lines may mean that the cel is a fan-drawn cel, i.e., not authentic. The ink used in making animation is not top grade, and UV rays will fade out the black lines quickly.
• Chipped off color. If the color appears to be missing, it could mean that there was once a sketch (called a genga) attached to it, and when it was removed, the ink came off, too. It could also have been handled too much.
• Is there a background? Backgrounds were used over and over, so if it shows a background, either the cel includes an original background on a separate sheet, the background isn't an authentic one used in that scene, or it's fan-made. Quite often cel collectors will either commission, buy or make their own backgrounds so they can have their cels framed.
• Smears, fingerprints, any damage to the acetate used to make the cel. You might request a closeup jpeg if you suspect there is damage to the cel material.
• If the sketch (genga) is stuck, prepare to accept the cel as is. Sometimes the sketch can be removed if it's only stuck in a small area, but prepare to lose the sketch if you successfully remove it. You can't have both.
• Gengas can also be very beautiful. Gengas are the preliminary sketches done in colored pencil and used to make the final sketch. They'll have directions written on them on how to finalize the cel. Dougas are the final sketch used to make the cel. They aren't as colorful but they're very clean.
  

Good luck and have fun collecting!