An adverbial clause is a group of words that functions like an adverb, providing information about when, where, why, how, or under what conditions something happens. These clauses usually begin with subordinating conjunctions such as because, although, if, or when. For example, in the sentence "I will go to the park if it stops raining," the clause "if it stops raining" explains the condition under which the action will occur. Adverbial clauses can be essential for adding context to a sentence. They can appear at the beginning or end of a sentence, and they often enhance the meaning by linking ideas. For instance, "Although it was late, she decided to call" uses the clause "Although it was late" to provide context for her decision.