adverb

mieux

better

C’est quand quelque chose est plus bon ou plus satisfaisant qu’avant ou qu’autre chose.

The word "mieux" in French means "better." It is the comparative form of the adverb "bien" (well).

Mieux is used to compare how well something is done or how good something is in relation to something else.
It is often used to describe improvement or a higher quality.

As an adverb: It modifies verbs, indicating that an action is done in a better way.
- Example: Il chante mieux que toi. (He sings better than you.)
As a comparative adjective: It can replace "plus bon" (which is incorrect) when talking about "good" in comparative form because "bon" corresponds to "meilleur" as an adjective, but "mieux" as an adverb.
- Example: Elle se sent mieux aujourd’hui. (She feels better today.)

Meilleur(e): This is the comparative form of the adjective "bon/bonne" (good). It is used before nouns.
- Example: Ce restaurant est meilleur que l’autre. (This restaurant is better than the other one.)
Mieux: Used as an adverb, modifying verbs, not nouns.
- Example: Tu devrais mieux étudier. (You should study better.)

Summary:

Use "meilleur(e)" to describe a noun (better quality).
Use "mieux" to describe an action or a state (better, usually related to verbs or adverbs).

If you want, I can also provide examples comparing "mieux" and "meilleur."