Audi AG is a German automobile manufacturer that designs, engineers, produces, markets and distributes luxury automobiles.

Audi oversees worldwide operations from its headquarters in Ingolstadt, Bavaria, Germany. Audi-branded vehicles are produced in nine production facilities worldwide.

Audi has been a majority owned (99.55%) subsidiary of Volkswagen Group since 1966, following a phased purchase of Audi AG's predecessor, Auto Union, from Daimler-Benz.Volkswagen relaunched the Audi brand with the 1965 introduction of the Audi F103 series.

The company name is based on the Latin translation of the surname of the founder, August Horch. "Horch", meaning "listen" in German, becomes "audi" in Latin. The four rings of the Audi logo each represent one of four car companies that banded together to create Audi's predecessor company, Auto Union. Audi's slogan is Vorsprung durch Technik, meaning "Advancement through Technology". However, since 2007 Audi USA has used the slogan "Truth in Engineering". Audi is among the best-selling luxury automobiles in the world.

Like most German manufacturing, at the onset of World War II the Auto Union plants were retooled for military production, and were a target for allied bombing during the war which left them damaged.

Overrun by the Soviet Army in 1945, on the orders of the Soviet Union military administration the factories were dismantled as part of war reparations. Following this, the company's entire assets were expropriated without compensation. On 17 August 1948, Auto Union AG of Chemnitz was deleted from the commercial register.These actions had the effect of liquidating Germany's Auto Union AG. The remains of the Audi plant of Zwickau became the VEB (for "People Owned Enterprise") Automobilwerk Zwickau or AWZ (in English: Automobile Works Zwickau).

The former Audi factory in Zwickau restarted assembly of the pre-war-models in 1949. These DKW models were renamed to IFA F8 and IFA F9 and were similar to the West German versions. West and East German models were equipped with the traditional and renowned DKW two-stroke engines. The Zwickau plant manufactured the infamous Trabant until 1991, when it came under Volkswagen control—effectively bringing it under the same umbrella as Audi since 1945.

Audi's sales grew strongly in the 2000s, with deliveries to customers increasing from 653,000 in 2000 to 1,003,000 in 2008. The largest sales increases came from Eastern Europe (+19.3%), Africa (+17.2%) and the Middle East (+58.5%). China in particular has become a key market, representing 108,000 out of 705,000 cars delivered in the first three quarters of 2009. One factor for its popularity in China is that Audis have become the car of choice for purchase by the Chinese government for officials, and purchases by the government are responsible for 20% of its sales in China.[38] As of late 2009, Audi's operating profit of €1.17-billion ($1.85-billion) made it the biggest contributor to parent Volkswagen Group's nine-month operating profit of €1.5-billion, while the other marques in Group such as Bentley and SEAT had suffered considerable losses. May 2011 saw record sales for Audi of America with the new Audi A7 and Audi A3 TDI Clean Diesel. In May 2012, Audi reported a 10% increase in its sales—from 408 units to 480 in the last year alone.

Audi manufactures vehicles in seven plants around the world, some of which are shared with other VW Group marques although many sub-assemblies such as engines and transmissions are manufactured within other Volkswagen Group plants.