1. As a conjunction meaning "or"
* Voulez-vous du café ou du thé ? (Would you like coffee or tea?)
* Il est grand ou petit ? (Is he tall or short?)
* Je vais au cinéma ou au théâtre. (I am going to the cinema or the theatre.)
2. As part of an interrogative expression meaning "where?"
* Où est la bibliothèque ? (Where is the library?)
* Où allez-vous ? (Where are you going?)
* Où as-tu trouvé ce livre ? (Where did you find this book?)
3. In some set expressions
* Où est-ce que... (Where is it that...)
* Où que... (Wherever...)
* D'où... (From where...)
Note: "Ou" is often followed by a comma in French, especially when it separates two clauses.
Let me know if you have any other questions! 😊