Many types of people are collecting coins for plenty of reasons. Casual coin collectors begin the coin collection by having coins found by chance. These coins may be an old coin found in circulation or change left for an international trip. In course of time, they acquire the interest to collect the coins. If their enthusiasm increases, random coins found in circulation are not enough to satisfy their interest.
If they heavily focused on coin collecting, they can buy coins from dealers or mint. Some people with more interest become generalists and collect a broad variety of historically significant coins. The Egypt king Farouk was a generalist with a collection of a wide range of coins. If the coin collecting people decide to focus on financial resources, then they are referred as a specialist. Some specialists focus on coins of a certain nation or historic period. Some will search for error coins. Some others might focus on currency, tokens, etc.
Completists are the collectors of a certain type of coin with a certain category. In recent years, coin collecting becomes an economic activity. Registry sets are private collections of coins. The grading services evaluate collections, seal the coins, and then register and publish the outcomes. The best specimens of coins will become compete among the dedicated collectors and they can lead to very high prices. Some enthusiasts focus the coin collection on a single country. Some may endeavor to attain a sample from every country that they issued. Instead of being satisfied with a single type of coins, many collectors collect the coins by year. Some may concentrate on the coins with distinguished mint marks. Usually the mint marks are more common. But sometimes intentionally or accidentally, some coins have different mint marks. A rare type of people is interested in the metallurgical composition of the coins.