between two complements of a ditransitive verb: donner des cadeaux à Jean /dɔ.ne de ka.do ∅ a ʒɑ̃/ ("give presents to Jean")[citation needed]
between two complete clauses: "Ils parlent et j'écoute." /il paʁl ∅ e ʒe.kut/ ("They talk and I listen.")
after certain words, for example et ("and"), and all singular nouns. This can help disambiguate between word uses: un précieux insolent /œ̃ pʁe.sjø ɛ̃.sɔ.lɑ̃/ (pronounced without liaison) could mean "an insolent member of the précieuses literary movement" (précieux can be a noun), but with liaison un précieux insolent /œ̃ pʁe.sjø.z‿ɛ̃.sɔ.lɑ̃/can only refer to a precious insolent person (précieux can also be an adjective).
In fixed expressions, singular nouns can allow liaison (accent‿aigu, fait‿accompli, cas‿échéant, mot‿à mot, de part‿et d'autre).
before "aspirated h" words: These are phonetically vowel-initial words that are exceptionally marked as not allowing liaison. Most of these words are written with a leading h (haricot, héros, haleter) which is not pronounced itself, but a few begin with a vowel or glide (onze, oui, yaourt). Note that some words beginning in h do experience liaison (e.g. homme in tout homme). Such words are said to begin with a mute h or h muet.
Grammars mention other contexts where liaison is "forbidden", despite (or precisely because) speakers sometimes do produce them spontaneously.