French écu

:"This article is about the medieval and early modern French currency, not the European Currency Unit (ECU) or an electronic control unit (ECU)."

The term écu may refer to one of several French coins. The first écu was a gold coin (the "écu d'or") minted during the reign of Louis IX of France, in 1266. "Ecu" (from Latin "scutum") means shield, and the coin was so called because its design included a shield bearing a coat of arms. The word is related to scudo and escudo. The value of the écu varied considerably over time, and silver coins (known as "écu d'argent") were also introduced.

In the 17th and 18th centuries, the name "écu" was applied exclusively to a large silver coin (introduced by Louis XIII in 1640) initially worth three "livres tournois". From 1690 to 1725 rates were unstable and new écus were issued, and existing écus revalued. After 1726 the final écu remained stable at six "livres tournois". The silver "écu" (sometimes also called the "louis d'argent") was further broken down into a 1/4 value coin (the "quart d'écu") and a 1/2 value coin (the "demi-écu"). For more on the 17-18th century currency system, see Louis (coin), livre tournois and Italian scudo.

The "écu" disappeared during the French Revolution, but the 5 francs silver coins minted throughout the 19th century were but the continuation of the old "écus", and were often still called "écu" by French people.

The "écu", as it existed immediately before the French Revolution, is approximately equivalent (in terms of purchasing power) to 20 euros or 25 dollars in 2006.