Short answers, pulled from the story.
Money is any item or verifiable record generally accepted as payment for goods and services and the repayment of debts in a particular country or context. Its primary functions are serving as a medium of exchange, a unit of account, a store of value, and sometimes a standard of deferred payment. William Stanley Jevons analyzed these four functions in Money and the Mechanism of Exchange in 1875.
The word money derives from the Latin moneta, meaning coin, by way of the French monnaie. The Latin word is believed to originate from the temple of Juno Moneta on the Capitoline, one of Rome's seven hills, which housed the mint of Ancient Rome.
According to Herodotus, the Lydians were the first people to introduce gold and silver coins, with the first stamped coins thought to be minted around 650 to 600 BC. Paper money was first used in China, developing from the late Tang dynasty into the Song dynasty, and in Europe it was first introduced in Sweden in 1661 by Stockholms Banco.
Fiat money is money whose value is not derived from any intrinsic value or guarantee that it can be converted into a commodity such as gold. It has value only by government order, usually as declared legal tender. Commodity money, by contrast, gets its value from the commodity it is made of, such as gold, silver, barley, or cowry shells.
The United States suspended the convertibility of the dollar to gold in 1971, making it one of the last countries to break away from the gold standard. No country anywhere in the world today has an enforceable gold or silver standard currency system.
In most countries, the majority of money is created as bank money by commercial banks making loans, recording those loans as deposits of borrowing clients under fractional-reserve banking. Bank money forms by far the largest part of broad money in developed countries, and by the 2000s most money existed as digital currency in bank databases.