In coin collecting, the condition of a coin is everything and is the key to determining its value. A coin in mint or uncirculated condition can be worth several hundred or even a thousand times more than a coin that is in extremely poor condition. In fact, some extremely rare coins can be considered priceless and have nothing to compare to. That example seems kind of obvious is is true of almost every type of collectible such as stamps, cars, baseball cards and more. Almost all collectors create systems to determine the the condition and value of a collectible.

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The most common one used for coins is the one adopted by the American Numismatic Association called the Sheldon system and numbers a coin between 1 and 70, where 70 represents a perfect specimen and 1 represents a barely identifiable coin.

The generally accepted scale of for how to grade coins from highest to lowest work something like this:

* Mint State (MS) 60–70: Uncirculated
* About/Almost Uncirculated (AU) 50, 53, 55, 58
* Extremely Fine (XF or EF) 40, 4-
* Very Fine (VF) 20, 25, 30, 35
* Fine (F) 12, 15
* Very Good (VG) 8, 10
* Good (G) 4, 6
* About Good (AG) 3
* Fair (FA, FR) 2
* Poor (PR, PO) 1

As most hobbies go, collectors of coins often have a theme around which they collect. A few popular themes include:

Country collections

Collectors may find coins from every country that ever minted a coin, or they may aim to collect every coin every minted by a particular country.

Year collections

Rather than collecting one type of coin, some collectors attempt to collect every type of coin minted by year. For example, a collector might collect one Lincoln cent for every year from 1909 to the present. This is one of the most common ways to collect US currency. In fact most bookstores or coin collecting stores sell specially designed books, or coin albums, for the purpose of collecting coins by year.

Mintmark collections

A mint mark determines where a coin was minted. US currency is minted in such places as Denver, San Francisco. When you look at a Lincoln penny, for instance, near its date, is a small letter that determines where it was minted. The letter D denotes Denver. The letter S is for San Francisco. When collecting by year and mint mark, it isn't enough to collect one coin for each year, but for each year collect every coin minted.