A dark, slightly sweet yet sour vinegar made either entirely or partially of grapes.

The province of Modena in Italy

Balsamic vinegar was primarily confined to Italy until the 19th century. Today, it is used all over the world.

The first documented mention of balsamic vinegar was in 1046 by Henry III, emperor of the Holy Roman Empire. 

Food, Fermentation, and Micro-Organisms by Charles W. Bamforth (2005) 

“The History of Traditional Balsamic Vinegar” www.italymagazine.com/dual-language/history-traditional-balsamic-vinegar

The Oxford Companion to Food. 3rd ed., by Alan Davidson and edited by Tom Jaine (2014)