What is a fronted adverbial?

A fronted adverbial is an adverb or adverbial that is placed at the start of a sentence. Many adverbials, including sentence adverbs (e.g., “unfortunately”), adverbial phrases (e.g., “after work”) and adverbial clauses (e.g., “because you are smart”), can be used as fronted adverbials.

When an adverb or adverbial is placed at the start of a sentence, it should be followed by a comma (e.g., “luckily, the train was on time”).