When do I use the subjunctive?

The subjunctive is used when there is an expression of doubt or when the thing being said is not factual. There are certain phrases which always trigger the subjunctive including 'Je veux que' or 'Il faut que' and phrases which trigger the subjunctive usually have 'que' before the verb (e.g. Je veux que tu ailles). Phrases which involve emotions or feelings such as 'Je deteste que' also trigger the subjunctive.Like in all instances of rules in a foreign language there are exceptions to the rule. One example in French is that the use of 'Je pense que' does not trigger the subjunctive, whereas the negative form 'Je ne pense pas que' does trigger the use of the subbjunctive in the verb that immediately follows. The subjunctive in French has a present, perfect, imperfect & pluperfect form.