A dollar is the basic unit of money in the United States and several other countries. When you buy something for five dollars, you're using five of these units to pay for it. The dollar is divided into 100 smaller units called cents, so a dollar equals 100 cents.

The United States dollar is one of the most widely used currencies in the world. It comes in paper bills (one dollar, five dollars, ten dollars, and higher) and coins (including the dollar coin, though it's rarely used). Each bill features a portrait of an important American: George Washington appears on the one-dollar bill, Abraham Lincoln on the five, and so on.

The dollar sign ($) is written before the amount: $5.00 means five dollars.

Beyond American money, the word dollar appears in the currencies of Canada, Australia, New Zealand, and other nations, though each country's dollar has a different value. A Canadian dollar isn't worth exactly the same as an American dollar, just as a British pound or Japanese yen represents a different amount of purchasing power.

The slang term buck means the same thing as dollar, so “five bucks” means five dollars. People sometimes say something costs “top dollar” when it's expensive, or that they got it “for a dollar” when they found a great bargain.