Baden is a historical region on the east bank of the Rhine in the southwest of Germany, now the western part of the Baden-Württemberg (state) of Germany.

It came into existence in the 12th century as the Margraviate of Baden and subsequently split into different lines, which were unified in 1771. It became the much-enlargedGrand Duchy of Baden through the dissolution of the Holy Roman Empire in 1803–06 and remained a sovereign country until it joined the German Empire in 1871, remaining a Grand Duchy until 1918 when it became part of the Weimar Republic as the Republic of Baden. Baden was bounded to the north by the Kingdom of Bavaria and the Grand Duchy of Hessen-Darmstadt; to the west and practically throughout its whole length by the River Rhine, which separated it from the Bavarian Rhenish Palatinate and Alsace in modern France; to the south by Switzerland, and to the east by the Kingdom of Württemberg, the Principality of Hohenzollern-Sigmaringen and partly by Bavaria.

After World War II in 1945, the French military government created the state of Baden (originally known as "South Baden") out of the southern half of the former Baden, with Freiburg as capital. This southern half of Baden was declared in its 1947 constitution to be the true successor of the old Baden. The northern half of the old Baden was combined with northern Württemberg as part of the American military zone and formed the state of Württemberg-Baden. Both states became states of West Germany upon its formation in 1949.