Coinage

Common coins come in several different denominations based on the relative worth of the metal from which they are made. The three most common coins are the Gold Piece (GP), the Silver Piece (SP), and the Copper Piece (CP).
With one gold piece, a character can buy a Bedroll, 50 feet of good Rope, or a goat. A skilled artisan can earn one gold piece a day. The gold piece is the standard unit of measure for wealth, even if the coin itself is not commonly used. When merchants discuss deals that involve goods or services worth hundreds or thousands of gold pieces, the transactions don't usually involve the exchange of individual coins. Rather, the gold piece is a standard measure of value, and the actual exchange is in gold bars, letters of credit, or valuable goods.
One gold piece is worth ten silver pieces, the most prevalent coin among commoners. A silver piece buys a laborer's work for half a day, a flask of lamp oil, or a night's rest in a poor inn.
One silver piece is worth ten copper pieces, which are common among laborers and beggars. A single copper piece buys a candle, a torch, or a piece of chalk.
A standard coin weighs about a third of an ounce, so fifty coins weigh a pound.