End Stop Punctuation, Fragments, and Commas

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End Stop Punctuation

When you reach the end of a sentence, you need a period, question mark, or exclamation point.


Use a period after a sentence that makes a statement or a request. Make sure that your statements have an independent clause (see handout on independent clauses).


Phrases or subordinate clauses standing alone are missing a subject or a verb or are stated in such a way that they cannot stand alone. Fragments can be useful in informal conversations, but they have no place in formal writing.

Examples of grammatical sentences:

Examples of fragments:

Examples of corrected fragments:

Nine Rules for Commas

1. Independent clauses are separated by a coordinating conjunction.

  1. You can remember these conjunctions with the mnemonic FANBOYS; For, And, Nor, But, Or, Yet, and So receive a comma.
  2. A comma placed between two independent clauses that are not joined by a FANBOYS creates a comma splice, an ugly grammatical mistake. Be sure to include a FANBOYS as well as a comma.

2. Introductory subordinate clauses and prepositional phrases receive commas.

Examples of subordinate clauses and prepositional phrases:

3. Items in a series receive commas.

Example of items in a series:

4. Serial comma

Grammarians disagree over whether a comma should be placed before the conjunction in a series (the underlined comma in example 2 below is a “serial comma”). However, confusion can be avoided by adding such a comma:

5. Multiple adjectives in a series are separated by commas, but commas are not used to separate adverbs and adjectives.

Examples of adjectives and adverbs:

6. Parenthetical elements (phrases and clauses) and interrupters receive commas when parentheses are not used.

Examples of interrupters and parenthetical elements:

7. Direct addresses—people or objects to which you are directly talking—are set off by commas.


8. Speech tags are separated from quoted speech by commas. Do not use a comma when the word “that” is present.

Examples of speech tags:

9. Appositives, phrases which restate a noun, are set off by commas.

Examples of appositives:

Credit: Lydia Fash, © 2008, 2009