Addresses in this articles are written with the district number preceding the street name, the same as street signs in Vienna. So 9., Badgasse 26 is Badgasse #26 in the 9th district. Hence you can also always tell what district you are in by the first number on street signs. Districts can also be made into a postal code by substituting the XX in A-1XX0 Vienna (0X for districts below 10), for instance A-1090 Vienna for the 9th district and A-1200 the 20th, and are sometimes referred to as such.
Common points of reference are often used in Vienna in addition to districts, most noteablly public transportation stops. Reference to U1/U4 Schwedeplatz or Schwedenplatz (U1, U4) means that something is near to the Schwedenplatz stop on the underground lines 1 and 4. Normally if the place is not directly at the subway stop you can ask around and find it easily.
The Vienna Tourist Board operates information and booking booths at the airport Arrival Hall, 7AM-11PM and in the center at 1., Albertinaplatz/Maysedergasse. Information and free maps are also avialible from the ÖBB InfoPoints and offices at train stations.
Vienna has 23 districts or wards know singularly as Bezirk in Austrian German. These function subordinatly to the city as decentralized adminstrative branches of the commune, as well as making local decisions. They vary immensely in size and each has its own flair.

-Innere Stadt (1st District)
-Leopoldstadt (2nd District)
-Landstraße (3rd District)
-Wieden (4th District)
-Margareten (5th District)
-Mariahilf (6th District)
-Neubau (7th District)
-Josefstadt (8th District)
-Alsergrund (9th District)
-Favoriten (10th District)
-Simmering (11th District)
-Meidling (12th District)
-Hietzing (13th District)
-Penzing (14th District)
-Rudolfsheim-Fünfhaus (15th District)
-Ottakring (16th District)
-Hernals (17th District)
-Währing (18th District)
-Döbling (19th District)
-Brigittenau (20th District)
-Floridsdorf (21st District)
-Donaustadt (22nd District)
-Liesing (23rd District)