An adverbial clause (adverb clause) is a clause in the sentence that functions as an adverb. In other words, it contains a subject and a predicate, and it modifies a verb. An adverbial clause is separated from the other clauses by any of the following subordinating conjunctions: after, although, as, because, before, if, since, that, though, till, unless, until, when, where, while
e.g. Nick passed neurology with the highest marks although the course was difficult. Adverbial clauses can also be placed before the main clause without changing the meaning.
e.g. Although the course was difficult, Nick passed neurology with the highest marks. * When an adverb clause introduces the sentence, it is set off with a comma.
There are different types of adverbial clauses: time, place, cause, result, purpose, manner or comparison, concession, and condition.