By vs Until - English In A Minute - YouTube

Hi guys! This is Kee from BBC Learning English,

and today I'm going to tell you the differences

between 'until' and 'by'.

We use 'until' to talk about doing something

up to a certain point in time.

If I say:

I have to take care of my dog until 5pm,

it means I will start taking care of my dog now

and stop taking care of it at 5pm.

On the other hand,

we use 'by' to talk about doing something

before a future time or deadline.

If I say:

I have to finish an essay by 5pm,

it means I can start any time

but I will make sure that at 5pm

I have finished writing the essay.

So, I may even finish it at 3pm or any time before 5.

So we use 'until' to describe doing something

up to a certain point in time

and we use 'by' to describe doing something

before a future time or deadline.