The Difference Between “Until” and “By”

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Lesson Transcript

Hi everybody, my name is Alisha.

Today we're going to be talking about the difference between by and until.

So let's get started.

Okay.

So first we're going to talk about by.

By marks a deadline for an action to finish.

By marks the point where an action completes or is replaced by another action.

So really think about using by to express a deadline.

Something is going to stop or you must finish an action at this point in time.

So we can think about by as marking some point in the future.

So by marks some point in the future where an action is going to finish.

An action is going to be completed.

So in an example sentence I have, I'll be at the office by 7 p.m.

So in this sentence the speaker is not at the office, but 7 p.m. is the deadline.

This is the point in time at which the speaker will be at the office.

The speaker is not at the office now, but by 7 p.m., by the 7 p.m. deadline, the speaker

will be at the office.

This will shows us, this is a future tense expression, and by shows us the deadline.

The point at which that expression or the point at which that action is going to be

completed.

So this is how we use by to think about it like a deadline.

Some point in time at which an action will be completed or finished.

Okay.

So let's continue on to the other grammar point for today, which is until.

Until also has a more casual form.

We can use till, t-i-l-l, or apostrophe t-i-l.

You might see both spellings used for until, till, or till.

In most cases, it's good to use until.

In casual speaking and maybe in casual writing, you can use the casual form.

But until is always polite and is always correct.

Okay.

So when we use until, let's talk about when to use until.

We use until to talk about a continuing situation or a continuing state now in the present or

in the future, but it's going to change or stop.

So the key difference, one key difference here perhaps is a continuing situation, a

continuing state.

With by, the nuance is a deadline.

Something is going to finish at a deadline.

Here however, until gives us the nuance of something that's continuing.

Something true now, for example, but that may not be true in the future.

Until marks the point where that action or that state is going to finish or change.

Okay.

So we can think of it rather than as a deadline, as a key point in the future somewhere where

action A continues until a point where we use until and then a second action begins.

Something is going to change at the until point.

With by however, we don't have the nuance of an action changing.

We only have the nuance of a deadline.

So here until is used to show that something different is going to happen or something

will finish, but there's going to be a change after the until point.

So for example, this sentence very similar to the by example sentence is I'll be at the

office until 7 p.m.

So here we have the future tense I'll, I will, I'll be at the office until 7 p.m.

This sentence shows us the speaker is at the office right now.

However, at 7 p.m., until shows us that 7 p.m. is the point at which the situation or

the state is going to change.

So at 7 p.m., the speaker is probably going to leave the office until shows us that right

here the action or the state is going to change.

So please keep that in mind until shows you a change in something by shows more of a deadline

for an action that is continuing.

So I hope that we can practice this in a few example sentences now.

Okay, so let's try to choose the correct word to use in these example sentences.

Should we use by or should we use until in these cases?

So the first one I have is he has to find a new job, blah, blah, blah, march.

So in this case, we see a point in time.

We can think about it.

Should we use by or until here?

If we use by, we see that the deadline, the deadline nuance matches here.

He has to find a new job by March.

If we use until, he has to find a new job until March.

There's no information in this sentence that shows us a hint or that gives us a hint about

how the action is going to change.

Until does not make sense for this question.

So we should use by in this case.

He has to find a new job by March is the correct answer for this sentence.

In the second sentence, I'm not going to go to bed, blah, blah, blah.

I finish this movie.

So in this sentence, we have at the end, I finish this movie.

So there's some action maybe that's continuing here and we have another action.

I'm not going to go to bed.

In this case, it's a negative.

So there are two actions here.

This is a pretty good hint that there's an action that's going to change at some point

instead of the nuance of a deadline.

So for this sentence, until is the best answer.

I'm not going to go to bed until I finish this movie.

This shows us that at this point, the point where I finish the movie, I'm going to go

to bed.

This marks the change in the continuing state or the continuing situation.

So the next sentence is they need to write their reports, blah, blah, blah, tomorrow.

So this sentence, there's no change in the sentence.

We don't have any hints about some kind of different action that's going to happen.

Instead, we have maybe what seems to be a deadline, some requirement here too.

So if we try to use until, it doesn't make sense.

There's no changing action.

We can't guess about what might happen in the future or a change that might happen.

So by is the best answer here.

They need to write their reports by tomorrow.

Tomorrow is the deadline.

So we can guess that tomorrow is the deadline here.

By shows us that it's the deadline in this case for this task.

All right.

Let's take a look at something a little bit different.

Here we have, we can't leave the house, blah, blah, blah, your mother calls.

So again, there are two situations, there are two actions involved in this sentence.

We have leave the house and your mother calls, makes a phone call.

So because there are two actions here, we can guess that there's some change that's

going to happen.

So because we learned that until marks a change in actions, we know that until is

the better answer here.

Okay.

We can't leave the house until your mother calls would be the correct sentence here.

All right.

So let's look at the next sentence though.

This one is a tricky sentence.

This one is a little bit difficult.

We have, I'm not going to be there, something, something, 8 p.m.

So here we have 8 p.m. at the end of a sentence, which looks like a deadline, right?

We have going to be there.

So should we use by or until for this sentence?

It's difficult because actually both are okay for this sentence.

I'm not going to be there by 8 p.m. is correct.

And I'm not going to be there until 8 p.m. is also correct.

However, the meanings are very different.

Just as we practiced in these two sentences, I'll be at the office until, I'll be at the

office by 7 p.m.

The same is true here.

I'm not going to be there by 8 p.m. means I'm not going to be there at 8 p.m.

It's not possible for me.

I can't go.

However, I'm not going to be there until 8 p.m.

This sentence means after 8 p.m. or beginning at 8 p.m. and after I'm going to be there.

So please be careful.

In some cases, both by and until are correct, but they change the meaning of the sentence.

Okay.

Let's continue to another example.

So the next example sentence is also a little bit difficult.

If my date doesn't arrive, something, something, 7 p.m., I'm leaving.

Okay.

So here we have, we do have two actions.

My date doesn't arrive, a negative point, and I'm leaving.

So it seems like there are two actions here.

However, we have this 7 p.m.

This marks a deadline, right?

So if my date doesn't arrive, there's some deadline here.

If this is not completed, something is going to happen.

The person is going to leave.

So in this case, 7 p.m. is showing a deadline.

So we have to use by.

If my date doesn't arrive until 7 p.m., we could use that, but it doesn't sound so natural.

So the nuance again here is of a deadline.

There's something that is going to happen at 7 p.m.

7 p.m. marks the end point in this situation.

So we use by here.

Okay.

Let's go to the next pair.

Again, these are very interesting points.

We have to leave the beach, blah, blah, blah, 10 a.m.

And we have to stay at the beach, blah, blah, blah, 10 a.m.

Okay.

So these two sentences I included because I wanted to show the emphasis of changing

actions and continuing actions.

So we can see the verbs are different here.

In the first sentence, we have leave.

So this is a change, leaving a location.

In the second sentence, I have stay, which shows a continuing action, stay in one place.

So here, as you can guess then, we have to leave the beach, blah, blah, blah, 10 a.m.,

some change, some deadline.

So we'll use by to show our deadline.

In the second sentence, we have to stay at the beach.

Stay shows a continuing action, and then it's going to finish here.

So we'll use until.

We have to stay at the beach until 10 a.m.

This shows us a continuing action, and maybe at 10 a.m. we'll leave the beach.

All right.

Let's go on to the next sentence.

I'm not going to travel abroad, blah, blah, blah, I learn English.

Okay.

So here, there's no time point.

There's no 10 a.m., 8 p.m., tomorrow, and so on.

So this is a little more complex, maybe.

We have travel abroad and learn English.

So it seems there's no real deadline here, but we have maybe a change.

Maybe this shows us some kind of change, learning English marks a change.

So I'm not going to travel abroad until I learn English.

This shows us that something different is going to happen in the future, so we should

use until to mark that change.

Okay.

Our last example sentence for today is we told him to wake up, blah, blah, blah, 6 a.m.

So once more, our last sentence may be a little bit simple, but 6 a.m. shows us an action,

You can see a lot of these use a time to mark a deadline for an action.

So here, we told him to wake up by 6 a.m.

This is the point at which something must happen.

So we should use by here.

Okay, great.

So those are a few example sentences that you can have a look at and think about when

you're trying to decide whether to use by or until.

Keep in mind, however, there are some cases where both by or until are correct, but the

meaning is going to change significantly depending on the one you use.

So I hope this lesson was useful for you.

If you have any questions or if you want to try to make an example sentence using by or