End punctuation and commas are crucial for clear communication. Periods, question marks, and exclamation points signal the end of sentences, while commas separate parts within them. These punctuation marks help readers understand the structure and meaning of your writing.

Proper use of end punctuation and commas can make your writing more effective. Commas guide readers through complex sentences, separating clauses, phrases, and list items. Mastering these punctuation rules will improve your writing's clarity and impact.

End Punctuation

Types and Functions of End Punctuation

• Period marks the end of declarative and imperative sentences, signaling completion of a thought
  • Used in abbreviations (Dr., Mr., etc.)
  • Employed in ellipses (...) to indicate omitted text or trailing thoughts
• Question mark concludes interrogative sentences, prompting a response or indicating uncertainty
  • Direct questions end with a question mark (What time is it?)
  • Indirect questions do not require a question mark (He asked what time it was)
• Exclamation point expresses strong emotion, emphasis, or urgency in a sentence
  • Conveys excitement, surprise, anger, or other intense feelings
  • Should be used sparingly in formal writing to maintain professionalism

Proper Usage and Common Mistakes

• Avoid using multiple end punctuation marks together (No: Who said that?!)
• Ensure consistency in punctuation style within a document
• Place periods and commas inside quotation marks in American English ("The cat is black," she said)
• Question marks and exclamation points go inside quotation marks only if they are part of the quoted material

Comma Usage with Clauses and Phrases

Introductory Elements and Coordinating Conjunctions

• Introductory phrases set the stage for the main clause, requiring a comma after them
  • After eating dinner, we went for a walk
  • In the blink of an eye, everything changed
• Coordinating conjunctions (FANBOYS: for, and, nor, but, or, yet, so) connect independent clauses
  • Use a comma before the coordinating conjunction when joining two independent clauses
  • The sun was setting, and the birds were returning to their nests

Dependent Clauses and Parenthetical Expressions

• Dependent clauses cannot stand alone as complete sentences, often beginning with subordinating conjunctions
  • When placed before an independent clause, a comma follows the dependent clause (While I was sleeping, the phone rang)
  • No comma needed when the dependent clause follows the independent clause (The phone rang while I was sleeping)
• Parenthetical expressions interrupt the flow of a sentence, providing additional information
  • Set off by commas on both sides (The concert, believe it or not, was completely sold out)
  • Include words, phrases, or clauses that can be removed without changing the sentence's core meaning

Appositives and Related Constructions

• Appositives rename or further explain a noun or pronoun in a sentence
  • Non-essential appositives require commas (My sister, a talented musician, performed at the recital)
  • Essential appositives do not use commas (The author John Steinbeck wrote "The Grapes of Wrath")
• Use commas to separate items in a series of three or more elements
  • Applies to words, phrases, or clauses in a list (She bought apples, oranges, and bananas)

Comma Errors and Conventions

Common Comma Mistakes and Their Corrections

• Comma splice occurs when two independent clauses are joined only by a comma
  • Incorrect: The sun was setting, the temperature was dropping
  • Correct: The sun was setting, and the temperature was dropping (add coordinating conjunction)
  • Alternatively, use a semicolon or create two separate sentences
• Avoid using commas to separate subject from predicate
  • Incorrect: The long and winding road, led us to the mountain
  • Correct: The long and winding road led us to the mountain
• Do not use commas to separate compound subjects or compound predicates
  • Incorrect: The cat, and the dog chased each other
  • Correct: The cat and the dog chased each other

Stylistic Choices and Regional Differences

• Serial comma (Oxford comma) placed before the final "and" in a list of three or more items
  • Used consistently in some style guides (red, white, and blue)
  • Omitted in other styles, particularly in journalism (red, white and blue)
  • Helps prevent ambiguity in complex lists
• American vs. British English comma usage differs in certain contexts
  • American English places commas and periods inside quotation marks
  • British English places them outside unless they are part of the quoted material
• Consider the intended audience and publication guidelines when deciding on comma conventions