savoir

"To know" a fact, or "to know how to" do something (always + infinitive, no preposition: je sais nager). This is the half of French's most notorious verb-pair confusion for English speakers — see connaître for the other half.

• Je sais parler japonais. — I know how to speak Japanese.
• Tu sais où elle habite ? — Do you know where she lives?
• Il ne sait pas la réponse. — He doesn't know the answer.

English only has one verb, "to know," for both facts/skills (savoir) and people/places (connaître) — so learners default to savoir everywhere. "I know Paris" is je connais Paris, never *je sais Paris.*

Often confused with connaître.

• expression Savoir-faire — Literally "knowing how to do" — borrowed into English by the late 1700s/early 1800s to mean practical skill or tact in handling a situation.
• expression Savoir-vivre — "Knowing how to live" — an 18th-century French term (documented from the 1740s-50s) for social etiquette and good manners, also borrowed into English.