Coin collecting is the collecting or trading of coins or other forms of minted legal tender.
Coins of interest to collectors often include those that circulated for only a brief time, coins with mint errors and especially beautiful or historically significant pieces. Coin collecting can be differentiated from numismatics in that the latter is the systematic study of currency. Though closely related, the two disciplines are not necessarily the same. A numismatist may or may not be a coin collector and vice versa.
Article Source: en.wikipedia.org