The Condorcet method or virtual round robin was invented by Marie Jean Antoine Nicolas Caritat, the Marquis de Condorcet in the eighteenth century. Like the Borda count or instant runoff voting, it is a preference-based system. But from these preferences, one constructs a Condorcet matrix of how many times each candidate beats the other candidates in the voters' preferences, and one then uses this matrix to find the winner.
A Condorcet winner is a candidate who beats all the other ones individually. But there need not be a Condorcet winner, like if the top candidates have a circular preference like A > B > C > A. There are several algorithms that various people have devised for disambiguating such cases, like the Schulze beatpath method, Copeland, ranked pairs, and minimax.
Though the Condorcet method has seldom been used in government elections, if ever, it has been used by several organizations internally.