What this coin looks like (obverse, reverse, mint mark location, special features, etc.): There were a few major varieties of the 1819 Capped Bust Half Dollar. The most common variety is simply the Normal Date type which features no errors or major notable features as depicted above.
Two major varieties are both 1819/8 Capped Bust Half Dollar overdate errors in which an 1819 date was struck over an 1818 date. This resulted in a "9" over "8" where parts of the underlying "8" appear within and around the "9". However - one variety features a small number "9" which is thinner and smaller while the other features a large "9" which is noticeably thicker and wider. The difference between the large 9 vs small 9 is depicted below in the example comparison image: