How are central banks set up in the eurozone?

What we think of as the European Central Bank is really the “Eurosystem”: the 19 central banks of eurozone countries plus the ECB itself. The vast bulk of ECB’s balance sheet—its assets and its liabilities—is held by the national central banks. They function as sort of branches of the broader ECB. This is a consequence of Europe’s imperfect union: All the eurozone countries retain their own central banks and their own banking systems, even though the system’s policies and rules...