Uster is a city and capital of the district Uster in the Swiss Canton of Zürich.It is the third largest city in the Canton of Zürich, with over 30,000 inhabitants, and is one of the twenty largest cities in Switzerland. Uster is located next to lake Greifensee.The official language of Uster is (the Swiss variety of Standard) German, but the main spoken language is the local variant of the Alemannic Swiss German dialect.The city of Uster received the Wakker Prize in 2001.