Bulgaria's Adoption of the Euro and the Eurozone Membership Process

The Balkan country of 6.4 million people is to make the switch from its national currency, the lev, to the euro on 1 January.

Here are basic facts about the currency union, also called the Eurozone, and how countries join it.

The euro is a shared currency and monetary system launched in 1999 when 11 EU member countries irrevocably fixed their currencies to the euro as an accounting currency, then swapped out the national notes and coins in 2002.