Élision (le → l', je → j')
Summary
Elision drops the final vowel of a few short words before a word starting with a vowel sound or mute h, and the gap is written with an apostrophe.
Explanation
A small, closed set of short words lose their final vowel when the next word begins with a vowel sound or a mute h, and an apostrophe marks the missing letter. The core members are the articles and pronouns le, la, je, me, te, se, ce, the negation ne, the prepositions de and the conjunction que, plus si (only before il/ils): le + ami → l'ami, je + aime → j'aime, de + eau → d'eau, ne + est → n'est, que + il → qu'il, si + il → s'il.
Crucially, elision is obligatory, not a stylistic option. It also changes the spelling, which sets it apart from liaison: liaison only adds a sound in speech (les‿amis) without touching the written form, whereas elision deletes a written vowel and inserts an apostrophe. This is why j'aime and l'école are the only correct written forms, and je aime or le école are simply wrong.
Elision is blocked before an aspirate h (h aspiré). Such words behave as if they began with a consonant, so the full vowel is kept and no apostrophe appears: le héros, la honte, le hibou, le haricot. Compare l'homme and l'heure (mute h, elision applies) with le héros and la hache (aspirate h, no elision). Because the two kinds of h look identical, the aspirate ones must be memorised; dictionaries usually flag them.
A handful of details round out the rule. la and ne also elide (l'amie, n'oublie pas), me/te/se elide as object pronouns (il m'aime, tu t'appelles), and ce elides before a vowel in c'est, c'était. The word si elides only before il/ils (s'il pleut) and never before elle (si elle, no apostrophe). Some fixed words and contractions behave specially: jusque becomes jusqu' (jusqu'à), lorsque/puisque/quoique elide before a few words (lorsqu'il), and presque keeps its e except in presqu'île.
In careful pronunciation the elided forms are simply read as one connected unit: j'aime is /ʒɛm/, l'école is /lekɔl/, qu'elle is /kɛl/. There is no pause or glottal stop where the vowel used to be. Mastering elision early makes both your spelling and your spoken rhythm sound markedly more native, because French strongly prefers consonant–vowel transitions over two vowels meeting across a word boundary.
Examples
j'aime l'école — I love school (je → j' and la → l' before vowels; read as /ʒɛm lekɔl/, one connected unit.)
Il pense qu'elle a raison. — He thinks she is right. (que → qu' before elle: /kɛl/; the e is dropped in writing and speech.)
Je ne sais pas s'il vient. — I don't know if he is coming. (si elides only before il/ils → s'il /sil/; it would stay si elle.)
C'est l'heure d'aller. — It's time to go. (ce → c', la → l' (mute h in heure), de → d': /sɛ lœʁ dale/.)
le héros et la honte — the hero and the shame (Aspirate h blocks elision: le/la kept, no apostrophe, /lə eʁo/, /la ɔ̃t/.)
Common mistakes
Je aime le école.
J'aime l'école.
Elision is obligatory, not optional. Short words like je, le, la, de, ne, que, me, te, se and ce must drop their final vowel before a word beginning with a vowel sound (or a mute h), and the gap is closed with an apostrophe: je + aime → j'aime, le + école → l'école. Leaving the full forms (je aime, le école) is a clear written and spoken error; the vowels are never both pronounced.
Related rules
elisionapostropheconnected-speechorthography