Short answers, pulled from the story.
Niccolò Machiavelli was a Florentine diplomat, author, philosopher, and historian who lived from the 3rd of May 1469 to the 21st of June 1527, during the Italian Renaissance. He has often been called the father of modern political philosophy and political science. He served as secretary to the second chancery of the Republic of Florence from 1498 to 1512.
The Prince, or Il Principe, is a manual on how to seize and hold royal power, written around 1513 and published in 1532. Machiavelli argued that a ruler must be willing to act unscrupulously, that it is better to be feared than loved, and that acquiring and keeping a state can require cruelty and deceit. The Catholic Church banned it in 1559 by placing it on the Index Librorum Prohibitorum.
Machiavelli lost his post when the Medici retook Florence in 1512 after Spanish troops defeated the Florentines at Prato. His name appeared on a list of possible sympathizers in a conspiracy against the Medici, and he was falsely implicated. He was tortured with the rope, denied involvement, and after three weeks was released and retired to his farm at Sant'Andrea in Percussina.
Machiavellian describes a form of politics marked by cunning, duplicity, or bad faith, taking its name from Niccolò Machiavelli. The term gained pejorative usage in the late 16th century as his works circulated widely. It is sometimes thought that the English nickname Old Nick for the Devil also derives from his name.
Machiavelli was an ardent supporter of republican politics, and it is well attested that he preferred a republic to a principality. His Discourses on Livy, written around 1517, became a central text of modern republicanism. He nonetheless believed a republic needed a single founder with absolute power, and his republic has been criticized for its harshness by thinkers such as Guicciardini and Montesquieu.
Scholars argue Machiavelli was a major influence on the Founding Fathers because of his favoritism for republican government. John Adams praised him in A Defence of the Constitutions of Government of the United States of America, ranking him alongside Algernon Sidney and Montesquieu as a defender of mixed government. Benjamin Franklin, James Madison, and Thomas Jefferson are also said to have followed his republicanism.