Historically considered, the evolution of money as a commodity is characterized by the tendency of metals to supersede all other forms of money in the more advanced communities, and by the tendency to progress from the less valuable to the more valuable metals. The result is that gold, which possesses the desired qualities to a higher degree than the other metals, has become pre-eminently the universal money article. The settlement of big purchases, debts, and balances is made in terms of, and by the transfer of, gold. For certain purposes, however - for example, small transactions - other metals are more serviceable, their lower value making possible a larger weight for small values. Hence in the United States the contemporary use, along with gold, of silver, nickel, and copper; these latter, however, are recognized as subsidiary to gold.