Cause/Reason: because, since, as Contrast/Concession: although, though, even though, whereas Condition: if, unless, provided that, as long as Time: when, while, as soon as, before, after, until Purpose: so that, in order that Place: where, wherever
Examples by Type
Cause (because): I stayed home because I was sick. Contrast (although): Although it was raining, we went out. Condition (if): If you study, you will pass. Time (when): I will call you when I arrive. Time (while): While I was cooking, the phone rang. Purpose (so that): He worked hard so that he could succeed. Negative Condition (unless): You won't pass unless you study.
💡 Comma Rule: If the dependent clause (subordinating conjunction + clause) comes first, use a comma. If it comes second, no comma is needed.