Pristine: An issue that looks like it has never been read. Perfect condition. As it would be were it a new issue on a newsstand.
Mint: A pristine issue with a mailing label. A perfect issue containing a flaw from the manufacturer or distributor. i.e.- a mis-cut page due to folding in the presses
Near Mint (Near Fine): Very few flaws of any kind. May have some minor flaws and possibly 1 or 2 moderate flaws. An issue that was carefully read and was taken care of. Color change in the paper due to its acidity is NOT a flaw. Color change due to the sun IS a flaw.
Very Good: A general well read issue that has been taken care of and not misused. Can have numerous flaws of both light and moderate extent and can have a few Major flaws such as creases or dog-ears.
Good: Can have numerous flaws of all levels and can have tears.
Fair: An issue in Good condition that is missing either the front or back cover.
Poor: An issue that is missing the front, back, or both covers. May be missing interior pages.