Casual coin collectors often begin the hobby by saving notable coins found by chance. These coins may be pocket change left from an international trip or an old coin found in circulation.
Usually, if the enthusiasm of the novice increases over time, random coins found in circulation are not enough to satisfy their interest. The hobbyist may then trade coins in a coin club or buy coins from dealers or mints. Their collection takes on a more specific focus.
Some enthusiasts become generalists and accumulate a few examples from a broad variety of historical or geographically significant coins. Given enough resources, this can result in a vast collection. King Farouk of Egypt was a generalist with a collection famous for its scope and variety.
Most collectors decide to focus their financial resources on a narrower, specialist interest. Some collectors focus on coins of a certain nation or historic period. Others will seek error coins. Still others might focus on exonumia such as currency, tokens or challenge coins. For example, John Yarwood of Melbourne is the first person to take a serious interest in British military money (especially tokens).
Some collectors are completists and seek an example of every type of coin within a certain category. Perhaps the most famous of these is Louis Eliasberg, the only collector thus far to assemble a complete set of known coins of the United States.
Coin collecting can become a competitive activity, as prompted by the recent emergence of PCGS (Professional Coin Grading Service) and NGC (Numismatic Guarantee Corporation) Registry Sets. Registry Sets are private collections of coins verified for ownership and quality by numismatic grading services. The grading services assess collections, seal the coins in clear plastic holders, then register and publish the results. This can lead to very high prices as dedicated collectors compete for the very best specimens of, for example, each date and mint mark combination.
Article Source: en.wikipedia.org