Learn Hardcore French: C'est ce qu'elle préfère.

Ce becomes C' before a word that starts with a vowel sound, to make pronunciation smoother.
Here it’s followed by est (pronounced like é), so ce est contracts to c'est.

Functionally, C' here is the grammatical subject of the sentence: C' = This / That / It.
So: C'est = It is / This is / That is.

Why are there two similar words, C' and ce, in the same sentence? Don’t they both mean “it/that”?

They look similar but they play different roles:

C' (from ce) in C'est is the main subject pronoun: It is / That is.
The second ce is a demonstrative pronoun meaning that / the thing.

The structure is:

C' (subject) est (verb to be) ce qu'elle préfère (a clause functioning as a "thing").

More literally:

C' = That
est = is
ce qu'elle préfère = what she prefers / the thing that she prefers

So the sentence is like saying: That is the thing that she prefers.

What exactly does qu' (from que) do in ce qu'elle préfère?

Here qu' is the relative pronoun que, shortened before a vowel:

Full form: ce que elle préfère
Spoken/written form: ce qu'elle préfère

Que here means that / which / what and introduces a relative clause:

ce = the thing
que = that (object of the verb)
elle préfère = she prefers

So ce qu'elle préfère literally = the thing that she prefers.

Grammatically:

elle is the subject of préfère
que (qu') is the direct object of préfère

Why is it qu'elle and not que elle?

French avoids having e + vowel at word boundaries. So:

que elle → becomes qu'elle

This is called elision: que drops its final -e and replaces it with an apostrophe when the next word begins with a vowel or a silent h.

Same pattern as:

je ai → j'ai
ne ai → n'ai
que il → qu'il

What is the difference between ce que and ce qui, and why is it ce que here?

ce que and ce qui both mean roughly what / that which, but they differ in grammar:

ce qui is used when what/that which is the subject of the verb that follows.
- Ce qui m'intéresse, c'est le français.
  = What interests me is French.
  (qui is the subject of intéresse)
ce que is used when what/that which is the object of the verb that follows.
- C'est ce qu'elle préfère.
  = That is what she prefers.
  (que is the object of préfère; the subject is elle)

In ce qu'elle préfère, elle is the subject doing the preferring, so ce (the “thing”) must be the object → use ce que.

How would you translate C'est ce qu'elle préfère word-for-word?

A very literal breakdown is:

C' = That / It
est = is
ce = the thing
qu' (que) = that / which
elle = she
préfère = prefers

So, ultra-literal:
That is the thing that she prefers.

Natural English:
That’s what she prefers. or That’s the one she prefers.

What’s the difference between C'est ce qu'elle préfère and Elle préfère ça?

Both can translate as She prefers that / this, but there’s a nuance:

C'est ce qu'elle préfère

More structured; often used to echo or emphasize a choice.
Focuses on the idea: That is the thing she prefers (among other possibilities).
Works well as a comment on a previous, more complex idea:
- Faire ça le matin ? C'est ce qu'elle préfère.
  Doing that in the morning? That’s what she prefers.

Elle préfère ça

Simpler, more direct.
Literally: She prefers that / this.
Ça is more informal and more concrete/pointing: something you can gesture at.

In many spoken contexts they’re interchangeable, but C'est ce qu'elle préfère sounds slightly more neutral or explanatory; Elle préfère ça sounds more casual and immediate.

Could we also say C'est ça qu'elle préfère? If so, what’s the difference?

Yes, C'est ça qu'elle préfère is possible and common.

Compare:

C'est ce qu'elle préfère.
→ More neutral: That’s what she prefers.
C'est ça qu'elle préfère.
→ Feels more pointing / emphatic, especially in speech:
- You point at something: That one / This thing — that’s the one she prefers.

ce is a bit more neutral and can refer to something more abstract;
ça feels more colloquial and usually refers to something quite concrete or just mentioned.

Why is it préfère and not another form of the verb préférer?

Préférer is being conjugated in the present tense, 3rd person singular:

elle préfère = she prefers

The accent pattern of préférer changes:

Infinitive: préférer (é — è — er)
je préfère
tu préfères
il / elle préfère
nous préférons
vous préférez
ils / elles préfèrent

In préfère, the second e takes a grave accent (è), which changes the pronunciation to an open eh sound. This is normal for this verb pattern and not a special meaning here—just normal conjugation.

Does ce que agree in gender or number with anything? Would it change if the “thing” was plural or feminine?

No, ce que itself is invariable:

Always ce que, no gender/number change.

Even if the thing referred to is plural or feminine, ce que stays the same:

C'est ce qu'elle préfère.
That’s what she prefers (singular or plural “thing”).
C'est ce qu'ils préfèrent.
That’s what they prefer.

Any agreement (gender/number) would show up elsewhere (adjectives, participles, etc.), not in ce or que here.

Is C'est ce qu'elle préfère a full sentence by itself, or does it need context?

It is a complete sentence, but it’s most natural as a response or comment on something already mentioned.

Typical use:

Parmi tous ces desserts, c'est ce qu'elle préfère.
Among all these desserts, that’s the one she prefers.
Regarde cette robe. C'est ce qu'elle préfère.
Look at this dress. That’s the one she prefers.

On its own, without context, you understand the structure, but you don’t know what “that” refers to.

How would you say “That’s what she prefers to do” in French?

You simply add the infinitive:

C'est ce qu'elle préfère faire.
= That’s what she prefers to do.

Structure:

C'est = It/That is
ce qu' = what / that which
elle préfère = she prefers
faire = to do

The pattern C'est ce qu'elle préfère + [infinitive] is very common:

C'est ce qu'elle préfère manger.
That’s what she prefers to eat.

How is C'est ce qu'elle préfère pronounced, including any liaisons?

A standard pronunciation in IPA:

C'est ce qu'elle préfère → /sɛ sə kɛl pʁe.fɛʁ/

Piece by piece:

C'est → /sɛ/
ce → /sə/ (a very short, neutral vowel)
qu'elle → /kɛl/ (sounds roughly like kel)
préfère → /pʁe.fɛʁ/

Notes:

There is no required liaison between ce and qu'elle; you simply say: [sɛ sə kɛl].
The qu' is pronounced like a k sound plus elle → k-elle.
In casual speech, the whole thing may run together quite quickly: [sɛ sə kɛl pʁe.fɛʁ].

Is there any difference in meaning between C'est ce qu'elle préfère and “That’s what she likes best”?

They’re very close in everyday use.

préférer literally means to prefer.
In English, “what she prefers” and “what she likes best” are often interchangeable.

So:

C'est ce qu'elle préfère.
can naturally be translated as:
- That’s what she prefers.
- That’s the one she likes best.

If you wanted to stress liking instead of preferring, you could also use:

C'est ce qu'elle aime le plus.
= That’s what she likes the most.
But in many contexts, C'est ce qu'elle préfère already implies “likes best.”