The relations necessarily established between banks by the processes of exchange, together with the regulations imposed upon them by law, custom, or business usage, constitute in each nation a banking system, which often reflects national characteristics and peculiarities of national history. A description of the systems that have been developed in the chief commercial countries of the present day will show how the principles described in the preceding chapters have been applied and developed, and will throw light upon the subject of banking machinery and methods which will be treated in the next chapter.