BY OR UNTIL
Both until and by indicate “any time before, but not later than.”
Until tells us how long a situation continues. If something happens until a particular time, you stop doing it at that time.
- They lived in a small house until September 2003. (They stopped living there in September.)
- I will be away until Wednesday.(I will be back on Wednesday.)
- We also use until in negative sentences.
- Details will not be available until January.(January is the earliest you can expect to receive the details.)
- If something happens by a particular time, it happens at or before that time. It is often used to indicate a deadline.
- You have to finish by August 31. (August 31 is the last day you can finish; you may finish before this date.)
- We also use by when asking questions.
- Will the details be available by December?(This asks if they will be ready no later than December.)