 As in the second of the two examples below, if the two sentences are separated by a semicolon and the second sentence starts with an adverb, this adverb is preceded by a semicolon and followed by a comma.Using commas to offset certain adverbs is optional, including "then", "so", "yet", "instead", and "too" (meaning "also").Commas are often used to enclose parenthetical words and phrases within a sentence (i.e., information that is not essential to the meaning of the sentence).