An adverb clause or adverbial clause is a dependent clause that functions as an adverb within a sentence by indicating time, place, condition, contrast,  concession, reason, purpose, or result. An adverbial clause begins with a subordinating conjunction such as if, when, because, or although and usually includes a subject and predicate. Adverbial clauses indicate time, place, condition, contrast, etc.  It modifies the whole clause rather than just a verb. An adverbial clause is classified according to its meaning.