Summary: When should you use 'by' and 'until'?.
By: Richard Flynn |Audience: All|Category: English Grammar Usage Articles & Notes
When do we use BY?
We use by to set a time limit for completion:
- It must be ready by Friday.
- It can be ready before Friday, but Friday is the final day. (By is a preposition here.)
When do we use UNTIL?
We use until when the activity continues throughout the period up to the time limit:
- I'll be here until five o'clock.
- Between now and five o'clock, I shall be here all the time. (Until can be a preposition (until five o'clock) or a conjunction (until you have finished.) )