Where do you use the subjunctive?
The subjunctive mood is how you express hypothetical situations and outcomes. It's the mood used to express wishes, hopes, desires, and any other imagined outcome you might describe in speech or writing. If you've ever written something that began with “If I were . . .,” you've written in the subjunctive mood.
Is subjunctive British or American?
The subjunctive is more common in American English and formal British English than it is in spoken or informal British English. It's used to refer to situations that are not real (but are desirable) or hypothetical situations.