Short answers, pulled from the story.
The name euro was officially adopted on the 16th of December 1995 in Madrid. Belgian Esperantist Germain Pirlot is credited with suggesting it in a letter sent to European Commission President Jacques Santer on the 4th of August 1995, though former German Finance Minister Theo Waigel also claimed credit in 2017.
Physical euro coins and banknotes entered circulation on the 1st of January 2002. The old national currencies were fully replaced by March 2002, following a changeover period that ran until the 28th of February 2002.
The euro banknotes were designed by Austrian designer Robert Kalina. His original drafts referenced specific structures including the Rialto bridge and the Pont de Neuilly; these were later made more generic, though the final designs still closely resemble those specific prototypes.
358 million people live in the eurozone. Over 200 million additional people worldwide use currencies pegged to the euro, including 182 million in Africa alone. A further nearly 3 million people in countries such as Montenegro, Kosovo, and Zimbabwe use the euro directly outside any formal EU framework.
The euro symbol € is based on the Greek letter epsilon, referencing the first letter of the word Europe, with two parallel lines added to signify stability. The design was selected by European Commission President Jacques Santer and Commissioner Yves-Thibault de Silguy from two finalists chosen through a public survey of thirty original proposals.
The eurozone crisis emerged in 2009 as fears of sovereign default followed the 2008 financial crisis. Greece was most acutely affected; Cyprus, Ireland, Italy, Portugal, and Spain were also significantly affected. The crisis was partly attributed to the euro area's lack of the institutional structures needed to enforce fiscal rules, with Germany and France themselves having broken the 3%-of-GDP deficit rule for three consecutive years by 2004.