Tu vs. toi
In French, both tu and toi translate to the informal, singular you. The key difference lies in their grammatical function within a sentence. Tu is a subject pronoun, while toi is a stressed or disjunctive pronoun used in various other contexts.
Tu
A1Tu is a subject pronoun. It is used exclusively as the subject of a verb, meaning it is the person or thing performing the action. It is always followed directly by its conjugated verb.
Tu parles très bien le français.
(You speak French very well.)
As-tu faim ce midi ?
(Are you hungry this afternoon?)
Tu as acheté un nouveau téléphone.
(You bought a new phone.)
Je pense que tu devrais te reposer.
(I think that you should rest.)
Demain, tu vas à la piscine.
(Tomorrow, you are going to the pool.)
Tu ne regardes jamais la télévision.
(You never watch television.)
Toi
A1Toi is a stressed pronoun (or disjunctive pronoun). It is used to emphasize you in various situations where tu cannot be used, such as after prepositions, in commands, for comparisons, or when standing alone.
Ce cadeau est pour toi.
(This gift is for you. (Used after a preposition pour))
Je sors avec toi ce soir.
(I am going out with you tonight. (Used after a preposition avec))
Toi, tu préfères le thé, mais moi, je préfère le café.
(You, you prefer tea, but me, I prefer coffee. (Used for emphasis or contrast))
Qui a fait ça ? C'est toi ?
(Who did that? Is it you? (Used after 'c'est'))
Mon frère est plus jeune que toi.
(My brother is younger than you. (Used in a comparison))
Lave-toi les mains avant de manger !
(Wash your hands before eating! (Used in an affirmative command))
Et toi, comment vas-tu ?
(And you, how are you? (Used to return a question or stand alone))
Ta sœur et toi, vous ressemblez beaucoup.
(Your sister and you, you look a lot alike. (Used as part of a compound subject))
Summary
In short, use tu when you is the subject performing the action of a verb (e.g., Tu manges - You eat). Use toi in most other cases: for emphasis (Toi, tu es fort), after prepositions like avec or pour (avec toi), in commands (Lève-toi), and in comparisons (plus grand que toi).