Book condition codes are as follows:
F = Fine (as new or almost as new)
VG = Looks great; may have faint or very light spine creases, minor or isolated edgewear, faint reading crease. Most likely will not have writing or stamps.
G = Will have spine creases, reading crease, edgewear, or writing/stamps, or any combination of above. Pages will be intact and attached; any exceptions will be noted.
You'll find some books with "minus" or "plus" signs after the codes (i.e., VG+ or F-). This indicates that they are a bit better, or somewhat less, than average for that condition. If something really stands out that supports this, I'll have a brief note at the end of the line.