One popular form of collecting is to acquire one example of every United States coinage design type. Rather than collect a denomination or series by date, a collector would instead seek to own one of every design or motif that was released. Doing so is popular for two reasons. First, it allows a collector to (largely) avoid key dates. Most series have a number of extremely scarce issues, which makes collecting by date very expensive. Conversely, if a “type” collector just needs one example of a series, he or she can buy a common date. Secondly, by buying a smaller number of coins in total, it is possible to concentrate one’s budget on higher quality specimens. If a collector spent $10,000 on a complete $2.50 Indian set, he or she would end up with a set in AU 58 condition. If the same $10,000 were spent on a single $2.50 Indian, the result would be one exceptional MS 66.
Given that most type collectors pick quality over rarity, the most common issues in a series are often known as “type” dates. The term “generic” is also used sometimes, especially among Silver Dollars and gold pieces. The basic message is that a type coin is one of the most common examples of a given design and is among the most available dates in higher grades. The date of a type coin is basically disregarded altogether.
In some series, there are a wide number of type dates, which in others a small number (or sometimes just one) carry that description. In the $3 Gold Princess series for instance, the 1874 and 1878 dates are the two obvious type dates as neither carries any kind of date premium. They are quite easy to find in all grades from VF through MS 65. Any date except 1874 or 1878 is worth more as a better date.
With all this being said, not all type coins are inexpensive. Some design types were made for a very short period of time in miniscule quantities; hence the most available date may still be very rare. The 1796-1797 Draped Bust Half Dollars are perfect examples. This two-year type is extremely rare with both dates being worth tens of thousands of dollars. A type collector of Half Dollars would have no choice but to pay up for a Draped Bust Half Dollar, which there are no common dates to choose.