The livre was the currency of France from 781 to 1794. Several different livres existed, some concurrently. The livre was the name of both units of account and coins.
The livre was established by Charlemagne as a unit of account equal to one pound of silver. It was subdivided into 20 sous (also sols), each of 12 deniers. The word livre came from the Latin word libra, a Roman unit of weight. This system and the denier itself served as the model for many of Europe's currencies, including the British pound, Italian lira, Spanish dinero and the Portuguese dinheiro.
This first livre is known as the livre carolingienne. Only deniers were initially minted, but debasement led to larger denominations being issued. Different mints in different regions used different weights for the denier, leading to several distinct livres of different values.
"Livre" is a homonym of the French word for "book" (from the Latin word liber), the distinction being that the two have a different gender. The monetary unit is feminine, la/une livre, while "book" is masculine, le/un livre.
The last coins and notes of the livre currency system were issued in the Year II of the Republic (1794). In 1795, the franc was introduced, worth 1 livre 3 deniers, and the first one-franc coin was struck in 1803. Still the word livre survived; until the middle of the 19th century it was indifferently used alongside the word franc, especially to express large amounts and transactions linked with property (real estate, property incomes or "rentes", cattle, etc...).