In ancient times the river was known as Latin: Dravus, cf. Sanskrit: द्रवति, dravati, "flow". The name is most likely of Celtic or Illyrian origin (see Old European hydronymy). The river gives its name to the dravite species of tourmaline.
The Drava (along with one of its tributaries, the Slizza) and the Spöl are the only two rivers originating in Italy that belong to the Danube drainage basin. Its main left tributaries (from the north) are the Isel (contributes 39 m³/s), the Möll (25 m³/s), the Lieser (22 m³/s), the Gurk (30 m³/s) and the Lavant (12 m³/s) in Austria, and the Mur (166 m³/s) near Legrad at the Croatian-Hungarian border. Its main right tributaries (from the south) are the Gail (45 m³/s) in Austria, the Meža (12 m³/s) and Dravinja (11 m³/s) in Slovenia, and the Bednja (? m³/s) in Croatia.
The Drava sources are located at the drainage divide between the market town of Innichen and neighbouring Toblach (Dobbiaco) in the west, where the Rienz River rises, a tributary of the Adige (Etsch). At Innichen itself the 16+ km Sextner Bach, originating near the Sextener Rotwand, joins the ~2 km long source creek. The river than flows eastwards and after 8 kilometres crosses into East Tyrol in Austria. At Lienz it flows into the Isel, sourced from the glaciers of the Venediger and Glockner Groups. The Isel (average discharge 39 m³/s) is almost three times larger than the Drava (14 m³/s) where they meet and, starting from the source of its tributary Schwarzach under the Rötspitze, the Isel (ca. 64 km) is also longer than the combined Drava and Sextner Bach (ca. 60 km) to that point.
The river then flows east into Carinthia at Oberdrauburg. The river separates the Kreuzeck range of the High Tauern in the north and the Gailtal Alps in the south, passes the Sachsenburg narrows and the site of the ancient city of Teurnia, before it reaches the town of Spittal an der Drau. Downstream of Villach, it runs along the northern slopes of the Karawanks to Ferlach and Lavamünd.