Commas and introductory elements | Punctuation | Grammar | Khan Academy

- [Voiceover] Hello grammarians!

Paige and I are here to teach you

about introductory elements in sentences

and how commas relate to them.

Paige, how should we define
what an introductory element is?

- [Voiceover] So, it's
pretty much something

that happens at the
beginning of a sentence.

It can be a dependent clause or an adverb.

But as we will see soon, it is something

that is separated off
with, of course, a comma.

- [Voiceover] Because
that's what commas do.

They are separators.

So, let's talk about
dependent clauses first.

And let me just write out a sentence

that begins with a dependent clause.

"When you come in, please
take off your shoes."

And I've made the difference
between the dependent clause

and the independent clause pretty clear.

So, this the dependent clause is purple,

the independent clause is green.

Is there a need for a comma here?

- [Voiceover] Of course.

- [Voiceover] Okay.
(Paige laughs)

Because we're leading
with a dependent clause,

and that means that this thing

can't stand on it's own, right?

It's like the ladder up against the tree.

Because an independent clause,

in green, can stand on its
own; a dependent clause cannot.

So, we need to differentiate it

from the rest of the sentence
by putting the comma there.

So, this is a dependent clause.

And this is an independent clause.

So, if you start a sentence
with a dependent clause,

you're gonna need to put
the comma in the middle

before you proceed to
the independent clause,

which is the part that makes it

an actual functioning sentence.

- [Voiceover] Right.

- [Voiceover] If you have it
the other way around though,

if it's just, "Please take off
your shoes when you come in,"

no need for a comma.

I'll show you.

So, I'm not sure why this is.

I think it may just sort
of be a style relic.

I'm not entirely certain.

I mean, if you go back in American history

and you look at the Federalist Papers

and you look at the way
that people used commas

in the 18th century, it doesn't
make a whole lot of sense,

relative to how we use commas today.

So, a lot of this is cultural.

But I can tell you that
when an independent clause

comes before a dependent
clause, you don't use a comma.

And if you are uniting
two independent clauses,

in the following sentence,
"I rode an elephant

"and then I ate a mango," these two things

are both independent clauses, right?

I rode an elephant.

Then I ate a mango, right?

These two things need to be connected

by this conjunction, and.

But that's not all.

They also need to be joined by a comma.

Now, you could also sub
out, if you wanted to,

get rid of this comma and this
and and put in a semicolon,

but that's a story for another time.

So, if you're uniting
two independent clauses,

just do comma and then a conjunction.

So, that's one way to think about

how to use commas for
introductory elements

like dependent and independent clauses.

But there's also another thing
I wanna introduce you to,

and that's sentence adverbs.

Follow us over to the next screen.

So, Paige, what is a sentence adverb?

How does it work?

- [Voiceover] So, we've been talking about

starting sentences with clauses,

but that doesn't always
have to be the case.

You can start a sentence with an adverb.

Like, let's say,
"Initially, I was afraid."

- [Voiceover] So, what is initially doing

in this sentence here, in this expression?

- [Voiceover] Basically, it's modifying

the whole rest of the sentence.

It's modifying the "I was afraid."

- [Voiceover] So, we're
gonna put a comma here

to separate it from the
rest of that expression.

That's why we call it a sentence adverb,

'cause it's not, this is
not the same as saying,

"I was initially afraid."

This is kind of, like you said,

modifying the entire expression.

Let's look at another example.

- [Voiceover] "Basically,
you're the greatest."

- [Voiceover] Aww, thanks, Paige!

So, we've got this word, basically,

and basically is modifying
the entire expression.

It's kind of qualifying the whole thing.

- [Voiceover] Right.

- [Voiceover] So, we're gonna put a comma

between this sentence adverb
and the sentence itself.

- [Voiceover] Exactly.

- [Voiceover] Cool, so, initially, Paige,

this seemed pretty complicated to me.

- [Voiceover] Right, but,
basically, I think we got it down.

- [Voiceover] All right,
we think that, essentially,

you can learn anything.

- [Voiceover] David out.
- [Voiceover] Paige out.