avant que

Example

Partons avant qu'il ne pleuve.

Do not write

Partons avant qu'il pleut.

Why

The action has not happened yet: subjunctive. The contrast with après que is the trap in this family, and it is on the DELF syllabus: avant que takes the subjunctive, après que takes the indicative. The ne is expletive and optional.

See the connector entry →