Country Collections – Obviously something of a catch-all phrase here. Many collectors will pursue coins of a particular country – frequently their own country or one to which they have an ancestral link. As a general statement a country collection would be too broad a notion and would probably have an additional approach (such as type or period) associated with it.
Series – A series collection is focused on a particular coin issue. A series collection would reflect the pursuit of some measure of completion, such as one example from each year. You would also expect that collector to be more concerned with minutia such as mint marks and die variations than you might see in other collection types.
Variations and Errors – Many collectors enjoy the hunt for the subtle and not so subtle irregularities that will naturally occur in the production of coinage. Variety collectors categorize these differences by how the how they occur and at what point in the minting process. There is even a registry of variations maintained.
Type Collections – In a type collection a representative example from each coin issue is collected. Type collections are frequently bound by some constraint or another such as country or time period.
Period Collections – A period collector will build collections bound by an historical period, perhaps a certain century or an entire era. Medieval and ancient coins are very popular. There are a surprising number of affordable, genuine coins from Greece, Rome and other ancient civilizations.
Tokens and Medals – Part of a larger field known as exonumia, the collection of coin-like items is a fun and fascinating complement to a more traditional coin collection. The field is vast, encompassing everything from private currencies, to military artifacts, to political memorabilia.