French is written using the Latin alphabet, plus five diacritics (the circumflex accent, acute accent, grave accent, diaeresis, and cedilla) and two ligatures (æ, œ).
The diacritics have phonetic, semantic, and etymological significance. Diactritics are sometimes omitted from capitalized letters.
· The grave accent ( ` ) à è ù
In French the grave accent has two uses. On the letter e it marks the distinct quality of the vowel: è [ɛ] and e [ə]. On the letters a and u it is used only as a grammatical mark that has no effect on pronunciation. On a it distinguishes the preposition à ("to") and the verb a (present tense of avoir); it is also used in the word déjà and the phrase çà et là. On u it is used only to distinguish où ("where") and ou ("or").
In French the acute accent is used only on the letter e, where it changes the vowel sound - it distinguishes é [e] and e [ə]. Often indicates the historical deletion of a following consonant (usually an s): écouter < escouter.
· The circumflex ( ˆ ) â ê î ô û
In French the circumflex over an e or o indicates the sound /ɛ/ or /o/, respectively. Most often indicates the historical deletion of an adjacent letter (usually an s or a vowel): château < castel, sûr < seur, dîner < disner. By extension, it has also come to be used to distinguish homophones: du ("of the") vs. dû (past participle of devoir "to owe"; note that dû is in fact written thus because of a dropped e: deu).
In French the diaeresis is often used to indicate that the second of a pair of vowels is to be pronounced as a separate vowel rather than being treated as silent or as part of a diphthong (naïve, Noël). French also uses the diaeresis to indicate syllabification in, for example, Gaëlle and païen. Diaeresis on ÿ only occurs in some proper names like Louÿs or placenames like L'Haÿ-Les-Roses and in modern editions of old French texts. Since the 1990, the diaeresis in words containing guë (such as aiguë or ciguë) was moved onto the u: aigüe, cigüe. ü is used in capharnaüm ("mess, shambles"), and a few proper names like Saül or Esaü.
· The cedilla (¸) ç
In French the cedilla is used before a, o, or u to indicate that it is read /s/ (unlike c, which is read /k/ before a, o, and u). It is not used before e or i, since c itself is read /s/ before e and i.
ay = [ɛji] before a consonant, [aj] elsewhere
c = [s] before i, e or y but [k] elsewhere
g = [ʒ] before i, e or y but [g] elsewhere
i = [ i ̭:] before vowels, but [i] elsewhere
ie = [i] at the end of a word, [j̃ɛ] before n, [je] elsewhere.
u = [ɥ] before vowels, but [y] elsewhere
x = [ks], [gs] or [gz] - usually [gz]
k and w only appear in loan words
y is used mainly loanwords but also in placenames.