The Medici Bank was one of the most prosperous and most respected in Europe. There are some estimates that the Medici family was, for a period of time, the wealthiest family in Europe. From this base, the family acquired political power initially in Florence, and later in wider Italy and Europe. A notable contribution to the profession of accounting was the improvement of the general ledger system through the development of the double-entry bookkeeping system for tracking credits and debits. This system was first used by accountants working for the Medici family in Florence.
The origin of the name is uncertain although its Italian meaning is "medical doctor". Members of the family rose to some prominence in the early 14th century in the wool trade, especially with France and Spain. Despite the presence of some Medici in the city's government institutions, they were still far less notable than outstanding families such as the Albizzi or the Strozzi. One Salvestro de' Medici was speaker of the woolmakers' guild during the Ciompi revolt, and one Antonio was sentenced to death in 1396. The involvement in another plot in 1400 caused all branches of the family to be banned from Florence's politics for twenty years, with the exception of two: from one of the latter, that of Averardo (Bicci) de' Medici, originated the Medici dynasty.
Averardo's son, Giovani di Bicci, increased the wealth of the family through his creation of the Medici Bank, and became one of the richest men in the city of Florence. Although he never held any political charge, he gained strong popular support for the family through his support for the introduction of a proportional taxing system.
Elder — ruled until the assassination of Alessandro de' Medici, first Duke of Florence, in 1537. This century-long rule was only interrupted on two occasions (between 1494–1512 and 1527–1530), when popular revolts sent the Medici into exile. Power then passed to the "junior" branch — those descended from Lorenzo the Elder, younger son of Giovanni di Bicci, starting with his great-great-grandson Cosimo I the Great. The Medici's rise to power was chronicled in detail by Benedetto Dei.
Cosimo and his father started the Medici foundations in banking, manufacturing - including a form of franchises - wealth, art, cultural patronage, and in the Papacy that ensured their success for generations. At least half, probably more, of Florence’s people were employed by them and their foundational branches in business.
Piero de' Medici (1416-1469), Cosimo’s son, stayed in power for only five years (1464-1469). He was called Piero the Gouty because of the gout that infected his foot, and it eventually led to his death. Unlike his father, Piero had little interest in the arts. Due to his illness, he mostly stayed at home bedridden, and therefore did little to further the Medici control of Florence while in power. As such, Medici rule stagnated until the next generation, when Piero's son Lorenzo took over.
Lorenzo de' Medici “the Magnificent” (1449-1492), was more capable of leading and ruling a city. To ensure the continuance of his family's success, Lorenzo planned his children's future careers for them. He groomed the headstrong Piero II to follow as his successor in civil leadership; Giovanni (future Pope Leo X) was placed in the church at an early age; and provided his daughter Maddalena with a sumptuous dowry when she made the politically advantageous marriage to a son of Pope Innocent VIII. When Giuliano, Lorenzo’s brother, was assassinated in church on Easter Sunday (1478), Lorenzo adopted his illegitimate son, Giulio de' Medici (1478-1535), the future Clement VII. Unfortunately, all Lorenzo's careful planning fell apart to some degree under the incompetent Piero II, who took over as the head of Florence after his father Lorenzo's death. Piero was responsible for the expulsion of the Medici from 1494-1512.
However, the Medici remained masters of Italy through their two famous 16th century popes, Leo X and Clement VII, who were de facto rulers of both Rome and Florence. They were both patrons of the arts, but in the religious field they proved unable to stem the advance of Martin Luther's ideas. Another Medici became Pope: Alessandro Ottaviano de' Medici (Leo XI).
The most outstanding figure of the 16th century Medici was Cosimo I, who, coming from relatively modest beginnings in the Mugello, rose to supremacy in the whole of Tuscany, conquering the Florentines' most hated rival Siena and founding the Grand Duchy of Tuscany.
Under Savonarola's fanatical leadership, many great works were "voluntarily" destroyed in the Bonfire of the Vanities (February 7, 1497). The following year, on May 23, 1498, Savonarola and his two young supporters were burned at the stake in the Piazza della Signoria, the same location as his bonfire. In addition to commissions for art and architecture, the Medici were prolific collectors and today their acquisitions form the core of the Uffizi museum in Florence. In architecture, the Medici are responsible for some notable features of Florence; including the Uffizi Gallery, the Boboli Gardens, the Belvedere, and the Palazzo Medici.
Although none of the Medici themselves were scientists, the family is well known to have been the patrons of the famous Galileo Galilei, who tutored multiple generations of Medici children, and was an important figurehead for his patron's quest for power. Galileo's patronage was eventually abandoned by Ferdinando II, when the Inquisition accused Galileo of heresy. However, the Medici family did afford the scientist a safe haven for many years. Galileo named the four largest moons of Jupiter after four Medici children he tutored.