The Use of By + Until
Summary: When should you use 'by' and 'until'?.
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: