The German language is officially used in all of Austria. Although English is taught in Austrian high schools, German is spoken in the country especially in tourist areas. There are Austrian minorities that speak Slavic languages. Standard Austrian German vocabulary used in official texts and schools is anchored from Austrian dictionary (Österreichisches Wörterbuch) published under the authority of the Austrian ministry of education, art and culture.
German is considered a pluricentric language meaning there are several standard versions of it. The German used in Austria is distinct from that of Germany or Switzerland. Austrian dialects are not the same as that of the variety of Standard German spoken by most Austrians.
In Vienna, the dialect spoken is Viennese German which belongs to the Austro-Bavarian dialects. There are expressions in the dialect that are not used in Lower Austria (the state surrounding Vienna). These expressions are not even understood by Austrians in the west of the city.
Viennese is a different form of Standard Austrian German and it is also distinct from other dialects spoken in Austria. There used to be four types of Viennese spoken in the different districts of Vienna. These were Favoritnerisch (Favoriten,10.Bezirk), Meidlingerisch (Meidling,12.Bezirk) Ottakringerisch (Ottakring,16.Bezirk), and Floridsdorferisch (Floridsdorf, 21.Bezirk). These are not spoken anymore and the entire city speaks a common dialect with usages that differ as one move further away from the city.
Viennese people are not to be expected to be fluent speakers of English as Austria is predominantly German-speaking. Although Vienna’s first district (with the most concentration of tourist) has people that speak English, the rest of the city speaks it less or not at all.
In your travel in Vienna, remember that Austrians have regard for academic titles. The society in this nation is hierarchical that people in this part of the world are touchy about their titles especially in the academe.
Useful German words for simple conversations include Bitte (please), Danke (thank you), and Enschuldegung (excuse me, pardon me). Greetings like Guten Tag (good day) or Gruss Gott (God’s greeting) and Guten Abend (good evening) would also come in handy. Salespeople in Vienna would appreciate foreign shoppers greeting them. “Guten Tag” or “Gruss Gott” would be enough.