**Until** is a preposition and conjunction that indicates a point in time or a duration of time before something happens or continues. Here are some examples of its usage:
1. I will wait **until** my friend arrives to start the meeting.
2. We can't go on vacation **until** we save enough money.
3. She stayed at the party **until** midnight.
4. The concert will run from 7 pm **until** 10 pm.
5. He will not eat anything **until** he finishes his homework.
6. **Until** I saw the proof, I didn't believe him.
7. They didn't speak to each other **until** the argument was over.
8. **Until** you finish your work, don't leave the office.
9. We won't know the results **until** tomorrow.
10. **Until** she learns to respect others' opinions, she will have problems with communication.
In each of these examples, «until» is used to indicate a specific point in time when something will happen, continue, or stop.