Connects/transitions independent and dependent clauses.
after, although, as, because, before, even if, even though, if, in order that once, provided that, rather than, since, so that, than, that, though, unless, until, when, whenever, where, whereas, wherever, whether, while, why
Ex. Ronnie begins to sneeze violently whenever he opens the door to greet a fresh spring day.
Sneezing violently > opening the door.