The subordinate clause supplies a time, reason, condition, and so on for the main clause. Time Reason Concession Place Condition Manner after before since when whenever while until as as . After the rain stopped, the dog ran into the mud to play. The snowman melted because the sun came out. Even though John fell asleep, the telephone salesman kept talking.
Conjunctive adverbs make up an even stronger category of conjunctions.
They show logical relationships between two independent sentences, between sections of paragraphs, or between entire paragraphs. James has a garage full of wood working tools. He might, however, have some metric wrenches, too. I do not recommend that you play with a stick of dynamite lit at both ends. Rather, a ham sandwich would be better for you.