R.W. JULIAN
A common, but popular, error coin is one that is struck off center. If the date is visible, it is worth more.
GOLDBERG
When beginning collectors survey the field of numismatics, they often follow the path of least resistance and simply collect by date and denomination, with little thought about the interesting byways that can be found in the coins of the United States. One of the most spectacular examples of not following the usual direction was seen in late 2004 when an alert collector discovered a variation on the Wisconsin state quarter issued that year.