When did euro banknotes and coins enter circulation?

Euro banknotes and coins entered circulation in participating countries on January 1, 2002.12

Prior to this, the euro had been introduced as a noncash monetary unit on January 1, 1999, serving as a unit of account for financial markets and businesses while national currencies remained in use for everyday transactions. By February 28, 2002, the euro became the sole legal tender for the initial 12 member states of the euro area, effectively replacing their respective national currencies.12