An ace is a playing card. In the standard French deck, an ace has a single suit symbol (a heart, diamond, spade, or club) located in the middle of the card, sometimes large and decorated, especially in the case of the Ace of Spades. This embellishment on the Ace of Spades started when King James VI of Scotland and I of England required an insignia of the printing house to be printed on the Ace of Spades. This insignia was necessary for identifying the printing house and stamping it as having paid the new stamp tax. Although this requirement was abolished in 1960, the tradition has been kept by many card makers. In other countries the stamp and embellishments are usually found on ace cards; clubs in France, diamonds in Russia, hearts in Genoa.
The word "ace" comes from the Old French word as (from Latin 'as') meaning 'a unit', from the name of a small Roman coin. It originally meant the side of a die with only one mark, before it was a term for a playing card. Since this was the lowest roll of the die, it traditionally meant 'bad luck' in Middle English, but as the ace is often the highest playing card, its meaning has since changed to mean 'high-quality, excellence'. This connotation has seen the word applied to an unreachable tennis serve, a successful fighter pilot and more generally as a person proficient in their field, especially a sporting field.
German ace/deuce of bells
Historically, the ace had the lowest value and this still holds in many popular European games (in fact most European decks, including the French and Latin suited decks, do not use the "A" index, instead keeping the numeral "1"). The folk tradition of "ace high" existed in some games as of the late 15th century, for example Three-card brag, a precursor to modern forms of poker. In most games popular in the English-speaking world, aces have the highest value of all cards in a suit like the game of Hearts. Many games, such as poker and blackjack, allow the player to choose whether the ace is used as a high or low card. This duality allows players in some other games to use it as both at once; some variants of Rummy allow players to form groups, or "melds", of rank K-A-2 or similar. This is known colloquially as "going around the corner".
It was not only the French deck which experienced this promotion, but some games involving the Swiss and German deck also evolved into using the daus (deuce) as the highest card. The ass (ace) and daus were conflated into a single card and the names are used interchangeably along with sau (sow) as early cards of that rank depicted a pig. Some decks in southern Germany use "A" for the index because "D" is reserved for Dame (Queen) in French suited decks. Confusion is also avoided as German suited decks lack numbered cards below "7" or "6". Despite using French suited cards, Russians call the ace a deuce (tuz), a vestige of a period when German cards were predominant in central and eastern Europe.