The modern French language does not have a significant stress accent (like English) or long and short syllables (like Latin). This means that the French metric line is generally not determined by the number of beats, but by the number of syllables (see syllabic verse; in the Renaissance, there was a brief attempt to develop a French poetics based on long and short syllables [see "musique mesurée"]). The most common metric lengths are the ten-syllable line (decasyllable), the eight-syllable line (octosyllable) and the twelve-syllable line (the so-called "alexandrin").
In traditional French poetry, all permissible liaisons are made between words. Furthermore, unlike modern spoken French (at least in the north of France), a silent or mute 'e' counts as a syllable before a consonant and is pronounced, but is elided before a vowel (where "h aspiré" counts as a consonant). When it falls at the end of a line, the mute "e" is hypermetrical (outside the count of syllables). (For more on pronunciation of French, see French phonology).
The ten-syllable and 12-syllable lines are generally marked by a regular syntactical pause, called a "césure" (cesura):
In traditional poetry, the césure cannot occur between two words that are syntactically linked (such as a subject and its verb), nor can it occur after an unelided mute e. (For more on poetic meter, see Poetic meter.)
For example:
Je fais souvent ce rêve étrange et pénétrant
d'une femme inconnue et que j'aime et qui m'aime...
(Paul Verlaine, "Mon rêve familier", from Poèmes saturniens)