Currency

The official currency of the United States is the United States dollar (USD $). In 1792 the newly independent United States chose the Spanish dollar as the unit of American currency, rather than the British pound. Now the currency is the most used in international transactions, and it is also the world's primary reserve currency.

Federal Reserve Notes, also United States banknotes（钞票，纸币）, are the banknotes currently used in the United States. American paper currency is issued in seven denominations（面额）: $1, $2, $5, $10, $20, $50, and $100. Although all denominations are the same size and same green color, the amounts are clearly printed on thenotes. The designs are also similar. So pay attention when counting out paper money. It’s easy to confuse the denomination and to make a mistake, for example, giving a $10 note when you intended to give $1.

US papercurrency has many nicknames and slang terms. The notes themselves are generally referred to as bills, so you can call a five dollar note as five-dollar bill. In oral English, you can also use the word buck to refer to dollars, such as one buck, or twenty bucks. Meanwhile, notes can also be referred to by the first or last name of the person on the front. For example, the $100 note,which has the portrait of Benjamin Franklin on the front, is nicknamed "Benjamin" or "Franklin".

      Coins of the United States dollar were first minted in 1792. Today, circulating（流通的）coins exist in denominations of 1¢, 5¢, 10¢, 25¢,50¢, and $1.00.

      One cent coin in the United States is also called penny, which is a copper-plated zinc coin. It has Abraham Lincoln on the head and the Lincoln Memorial on the tail.

      Nickel is the name of 5 cents. It’s made of a nickel and copper blend, which is larger than a penny.

      Dime refers to a 10¢ coin. Even though the worth of it is higher, its size is smaller than a penny.

      Quarter equals to 25 cents. It’s larger than a nickel. Quarters are the mostcommonly used coin in people’s daily life, as many coin-operated machines, such as washer, dryers, airport trolleys（手推车）accept only quarters.

      Half dollar is worth 50cents, and it’s the largest of US coins.

      One dollar coin is also called GoldenDollar. It features Native American heroine Sacagawea on the front. Nowadays, both the half dollar and golden dollar are not frequently used as other coins,and they are regionally circulated in some bigger cities.