The Sturmabteilung (German: [ˈʃtʊʁmʔapˌtaɪlʊŋ] (listen); SA; literally "Storm Detachment" or Stormtroopers) was the original paramilitary wing of the Nazi Party. It played a significant role in Adolf Hitler's rise to power in the 1920s and 1930s. Its primary purposes were providing protection for Nazi rallies and assemblies, disrupting the meetings of opposing parties, fighting against the paramilitary units of the opposing parties, especially the Roter Frontkämpferbund of the Communist Party of Germany (KPD) and the Reichsbanner Schwarz-Rot-Gold of the Social Democratic Party of Germany (SPD), and intimidating Romani, trade unionists, and especially Jews.

The SA were colloquially called Brownshirts (Braunhemden) because of the colour of their uniform's shirts, similar to Benito Mussolini's blackshirts. The official uniform of the SA was a brown shirt with a brown tie. The color came about because a large shipment of Lettow-shirts, originally intended for the German colonial troops in Germany's former East Africa colony, was purchased in 1921 by Gerhard Roßbach for use by his Freikorps paramilitary unit. They were later used for his Schill Youth organization in Salzburg, and in 1924 were adopted by the Schill Youth in Germany. The "Schill Sportversand" then became the main supplier for the SA's brown shirts. The SA developed pseudo-military titles for its members, with ranks that were later adopted by several other Nazi Party groups, chief amongst them the Schutzstaffel (SS), which originated as a branch of the SA before it was separated from it after the Night of the Long Knives.

After Adolf Hitler ordered the Night of the Long Knives (die Nacht der langen Messer) in 1934, he withdrew his support for the SA. The SA continued to exist but lost almost all its influence, and was effectively superseded by the SS, which had carried out Hitler's orders in the purge, and thereafter was formally removed from the SA. The SA remained in existence until after Nazi Germany's final capitulation to the Allies in 1945, after which it was disbanded and outlawed by the Allied Control Council.