Appenzell (or Appenzellerland) is a region and historical canton in the northeast of Switzerland, entirely surrounded by the Canton of St. Gallen.

Appenzell became independent of the Abbey of St. Gallen in 1403 and entered a league with the Old Swiss Confederacy in 1411, becoming a full member in 1513. It has been divided since into Appenzell Innerrhoden and Appenzell Ausserrhoden since 1597 as a result of the Swiss Reformation.

The territory of Appenzell as a geographical entity is known as Appenzellerland or (erroneously^{[citation needed]}) as das Appenzell. In political contexts, the two cantons are referred to as beide Appenzell ("both Appenzells").

The name Appenzell derives from Latin: abbatis cella) "cell (i.e. estate) of the abbot". This refers to the Abbey of St. Gall, which exerted a great influence on the area. By the middle of the 11th century the abbots of St Gall had established their power in the land later called Appenzell, which by that time was thoroughly Alemannic.

By about 1360, conflicts over grazing rights, taxes, and tithes were causing concern for both the abbot and the farmers of Appenzell. Both parties wanted to protect their rights and interests by joining the new Swabian League. In 1377 Appenzell was allowed to join the League with the support of the cities of Konstanz and St. Gallen (the city of St. Gallen was often at odds with the neighboring Abbey of St. Gall). With the support of League, Appenzell refused to pay many of the gifts and tithes that the Abbot Kuno von Stoffeln demanded. In response to the loss of revenue from his estates, Kuno approached the Austrian House of Habsburg for help. In 1392 he made an agreement with the Habsburgs, which was renewed in 1402. In response, in 1401 Appenzell entered into an alliance with the city of St. Gallen to protect their rights and freedom.