oder
or
Connects two or more alternatives between which one can or must choose.
Fahren wir mit dem Zug oder nehmen wir das Auto?
Are we going by train, or are we taking the car?

or
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or
Connects two or more alternatives between which one can or must choose.
Fahren wir mit dem Zug oder nehmen wir das Auto?
Are we going by train, or are we taking the car?

The conjunction 'oder' (or) connects two main clauses without changing the word order. The verb of the second clause remains in position 2, directly after the subject.
Wir gehen heute ins Kino, oder wir bleiben zu Hause und schauen einen Film.
We are going to the movies today, or we are staying home and watching a film.
The position in the sentence helps you recognize the meaning. If 'oder' (or) stands between two options, it is an alternative. If it stands at the end of a sentence before a question mark, it is a confirmation question.
Möchtest du Tee oder Kaffee?
Would you like tea or coffee?
As a question particle, 'oder?' (right?) always stands at the end of the sentence, separated by a comma. It turns a statement into an informal question used to seek agreement.
Du kommst morgen zur Party, oder?
You're coming to the party tomorrow, right?
In the meaning of 'correction', 'oder' (or) is often used in the fixed expression 'oder genauer gesagt' (or more precisely). This lets you make a previous statement more precise or correct it.
Wir treffen uns nächste Woche, oder genauer gesagt, am Montag um zehn.
We are meeting next week, or more precisely, on Monday at ten.
and
'und' and 'oder' both connect words, parts of a sentence, or sentences. The difference is important: 'und' joins things together, so both apply. 'oder' presents alternatives that you can choose between, or where it is not clear which one applies. Learners may confuse them because both stand as connectors between two parts. A practical tip is: with 'und', you take A plus B. With 'oder', it is about A or B as a possibility.

Nach der Arbeit geht Moritz ins Kino oder bleibt zu Hause.
After work, Moritz goes to the cinema or stays at home.
Herr Neumann nimmt im Zug Kaffee und ein Sandwich mit.
Mr. Neumann takes coffee and a sandwich with him on the train.