A parenthetical element or phrase, also known as an interrupter, adds extra detail or information and isn’t essential to the framing sentence. A parenthetical element can be removed from the sentence leaving a complete sentence.

Parenthetical elements can occur at the beginning, in the middle, or at the end of a sentence. If used at the beginning of a sentence, is is followed by a comma. When it is used at the end of a sentence, it is preceded by a comma. When the parenthetical element is in the middle of a sentence, it is offset by a comma on each side.

Parenthetical elements serve one of eight functions.

Eight Types of Parenthetical Elements

1. Introductory Phrase
   • Introduces something and sets the stage for the rest of the sentence
   • Does not have a subject and verb
   • Cannot stand alone as a complete thought
   • Describes how, when, where, or why
   • Example: When Mary was at the park, she lost her keys.
2. Interjection
   • A word or phrase that expresses emotion, sound, or a simple yes or no
   • Can appear at the beginning, middle, or end of a sentence
   • Also capable of standing alone
   • Example 1: Mmmm, that cake smells delicious.
   • Example 2: The test was, well, harder than I expected.
   • Example 3: You forgot to set the alarm again, huh?
3. Aside
   • a remark that isn’t directly related to the subject of the sentence
   • often denotes a sarcastic, apologetic, or ingratiating attitude
   • Example: He was, as you can imagine, upset when he heard the news.
4. Appositive
   • A noun, noun phrase, or noun clause which sits next to another noun to rename it, describe it in another way, define it, or modify it
   • Example 1: Jack introduced us to his wife, Jill, at the top of the hill.
     
     In the above example, it should be noted that the use of the commas with his wife, Jill, tells us that Jack has one wife and her name is Jill. If the commas are removed, then Jack has several wives and we are identifying one wife by the name Jill.
   • Example 2: Carla’s desk, the biggest disaster area in the office, is littered with papers everywhere.
5. Absolute phrase
   • Contains at least a noun or pronoun and a participle
   • May include additional modifiers and/or objects
   • Can occur at the beginning or end of the sentence and between a subject and verb
   • Modify an entire sentence, indicating something related happening at the exact same moment
   • Example 1: Her mind racing uncontrollably, Sherry threw her clothes into the suitcase.
   • Example 2: The mountain climber, his hands bleeding, pulled himself onto the ledge.
   • Example 3: Missy hid under the blankets, trembling and crying.
6. Free modifier
   • A phrase or clause that modifies either the main clause or another free modifier
   • Can be moved between the beginning, middle, and end of the sentence while retaining the meaning of the sentence
   • Example 1: Rapunzel, leaning out the window, let down her hair.
   • Example 2: Leaning out the window, Rapunzel let down her hair.
   • Example 3: Rapunzel let down her hair, leaning out the window.
7. Summative modifier
   • Appears at the end of a sentence
   • Summarizes an idea expressed in the sentence with a noun or noun clause and adds supplemental information
   • Example 1: The knight lost the fight, a defeat that would change his future.
   • Example 2: Mamma Mia’s serves a delicious chicken parmigiana, a house specialty that tantalizes your palette with the taste of Italy.
   • Jennifer would graduate tomorrow, a day she had anticipated all year.
8. Resumptive modifier
   • Resumes a sentence where it left off by repeating a word or phrase, which creates an echo-like effect for the end of the original sentence, and adds additional detail or information
   • Shifts the emphasis of a sentence from the main verb of the subject, usually to whatever information is found in the object position
   • Example 1: Marcus faced his biggest fear, a fear that had haunted him since childhood.
   • Example 2: Katherine gazed up at the night sky, a dark night sky with a red moon.