Coins are so versatile and easy to handle that they have long been the most widely used form of money in the world. However, they are also documents that reveal information about themselves, and are therefore essential to knowing our own history. Inspecting a coin tells us how much it is worth, the authority that issued it, the moment it was made, and the mint where it was struck.
The real de a ocho or “piece of eight” is an excellent example. The obverse of a "piece of eight” of Charles III bears the likeness of the king who ordered it minted. This image is encircled by an inscription that gives his name (Carolus) and the year it was struck (1780). On the reverse we find its value, eight reales, indicated by the number 8 and the letter R, and the mint where it was made, Mexico City, represented by a capital M with an O on top.
Present-day coins provide similar information. For instance, if we analyse a one-euro coin, we learn that it was issued by King Juan Carlos I, whose effigy appears in the middle of the obverse side. In the centre of the coin is the mark of the Madrid mint, a capital M with a crown above. Below we find the date of issue, the year 2001. Further to the right, the reverse is almost entirely occupied by the coin’s value, in this case a number 1 on the left side, and the word EURO on the right, engraved on a map of Europe.