Alsace is the fourth-smallest of the 26 regions of France in land area (8,280 km²), and the smallest in metropolitan France. It is also the sixth-most densely populated region in France and third most densely populated region in metropolitan France, with ca. 220 inhabitants per km² (total population in 2006: 1,815,488; January 1, 2008 estimate: 1,836,000). Alsace is located on France's eastern border and on the west bank of the upper Rhine adjacent to Germany and Switzerland. The political, economic and cultural capital as well as largest city of Alsace is Strasbourg. Due to that city being the seat of dozens of international organizations and bodies, Alsace is politically one of the most important regions in the European Union.

The name "Alsace" derives from the Germanic Ell-sass, meaning "Seated on the Ill", a river in Alsace. The region was historically part of the Holy Roman Empire. It was gradually annexed by France in the 17th century under kings Louis XIII and Louis XIV and made one of the provinces of France. Alsace is frequently mentioned in conjunction with Lorraine, because German possession of parts of these two régions (as the imperial province Alsace-Lorraine, 1871–1918) was contested in the 19th and 20th centuries, during which Alsace changed hands four times between France and Germany in 75 years.

Although Alsace is historically a German dialect speaking region, today most Alsatians speak French, the official language of the country they have been a part of for most of the past three centuries. However, about 39% of the local adult population, but probably less than 10% of the children, are still fluent in the Alsatian language.