While thousands of different coins exist, three main types can be identified: regular issue coins, circulating commemoratives, and non-circulating legal tender. Regular issue coins are the coins used on an everyday basis. The infrequent changes that are made to this type of currency is usually for security reasons.
A commemorative coin is a legally issued coin with a special design or message to bring attention to a person or event. A circulating commemorative coin can be used as real currency, but is only issued for a limited time to commemorate a person or event. While non-circulating legal tender can be used for regular purchases, it is intended only for decorative purposes or as a souvenir.
The United States Congress began allowing the U.S. Mint to produce commemorative coins to celebrate and honor American people, places, events, and institutions starting in 1982. These coins often help raise money for specific causes. When a commemorative coin is purchased, a portion of the proceeds go to a chosen organization or project. Since 1982, $418,000,000 has been raised through the purchase of commemorative coins. This money has been used to build museums, maintain monuments such as the Vietnam Memorial, and restore historical sites like George Washington's home. This money has also helped support various Olympic programs as well as many other endeavors.
Some numismatists get a start in coin collecting with commemoratives. Then, with increased knowledge, they move onto an interest in rare or foreign coins. Commemorative coins serve as a general introduction to the wide world of coin collecting.
The United States Mint website has a lot of good information on current commemorative coin collections available for purchase. Visit their site at www.usmint.gov. You can also find commemorative coins at online coin brokers and dealers.
Some of the more popular commemorative collections currently on the market include the State Quarters series, the Ultimate Silver Eagle Collection, and the Westward Journey Nickel Collection from 2005.
When buying coins, especially commemoratives, be sure to work with reputable dealers. Many collectors buy and sell at online sites like eBay or other auctions. Some of these online auctions do offer guarantees that aim to protect the bidder, but one must be diligent in reading the fine print before bidding. The competition on some auctions can be intense, and an auction can go on for a lone time. Not quite true auctions, many established coin dealers may have an online store that they advertise through auction sites. This might be in addition to their physical store. One advantage to online stores is that you can often view a digital computer scan of the coins listed for sale that will help you make good purchasing decisions.
Coin collecting magazines are also good sources of buying coins. Unfortunately it's not always possible to view the coins you are buying, and anything bought "sight unseen" comes with an inherent risk. If you buy from a dealer who advertises in a magazine, be sure to check to see if they belong to any of the professional coin dealer organizations mentioned above. Make sure the dealer has a fair return policy and do not start out with major purchases before developing faith in the seller. It is safer to buy certified coins and modern coins through mail order than it is to buy older coins that may have been cleaned to look like a higher grade of coin.
The American Numismatic Association and the American Numismatic Society also have lists of recommended dealers available on their websites. Membership in these societies assures the buyer that the dealer will be held to certain standards of integrity and conduct, and the buyer will generally be safer than when working with a private dealer.