What is the use of the subjunctive in French?

The subjunctive is a mood and not a tense unlike the perfect, imperfect, present and future. It is used to express doubt, desire, commands and fears. For example "il faut que" (command), j'ai peur que (fear), je souhaite que (desire), j'ai doute que (doubt).there are certain phrases which trigger the subjunctive which must be learned and there are endings, as with all verbs, which correspond to the pronoun. i would recommend learning the conjugation for these verbs: avoir, etre, faire, vouloir, pouvoir and devoir (mainly modal verbs).