The Grammar Guru: Commas after introductory elements

An avid coffee drinker, the Grammar Guru appreciates a good cup of joe.
An avid coffee drinker, the Grammar Guru appreciates a good cup of joe.

Mekita Rivas, SNR communications associate, publishes a biweekly feature called "Grammar Guru."

Every other week, the Grammar Guru will share writing tips to help make your work as polished as possible. Some of these tips may address common spelling errors, while others will examine the many nuances of the English language.

Grammar Guru Tip #30
Introductory elements consist of clauses, phrases and words that appear before the main clause of the sentence. Essentially, they prepare your readers for what the sentence is really about, or the meat of the sentence.

Introductory clauses and phrases that require an offsetting comma include prepositional phrases and clauses, infinitive phrases, participle phrases, dependent/subordinate clauses, nonessential appositive phrases and absolute phrases.

For the man who ran a marathon, the race seemed to go on forever. (This is a prepositional introductory clause because it has a subject (man) and a verb (ran).)

In the nighttime, people have a harder time driving. (This sentence contains a prepositional introductory phrase because there is a subject (nighttime), but no verb).

To stay up all night, the student had to drink eight cups of coffee. (The phrase starts with an infinitive, which is the word "to" followed by a simple verb.)

Walking into the store, the customer realized he forgot his wallet. (The phrase starts with a present or past participle of a verb. Present participles for regular verbs end with "ing," and past participles for regular verbs ending with "ed.")

If you didn't do the laundry, you aren't going to have any clean clothes. (The clause starts with either a subordinate conjunction, such as after, while or if, or a relative pronoun, such as which, whichever or who. The clauses cannot stand on their own because they are incomplete thoughts.)

An excellent professor, my father taught me everything about British literature. (These phrases are modifying ones that immediately precede the noun or pronoun they modify. They provide additional meaning or information to the sentence as a whole.)

Their clothes ratted and torn, the campers were relieved to take a warm shower. (These phrases have a noun or pronoun, a participle (a form of a verb) and any relevant modifiers. They do not modify one word or subject; instead, they modify the entire sentence by providing additional information.)

Need some grammar guidance? The UNL Style Guide ( is a great resource for all university employees. If you have writing questions that the style guide doesn't answer, feel free to email the Grammar Guru at